Chapter Summaries

Ye Yu used determination to restrain and destroy Scarlet, but his LOVE rose to LV 10 and his urge to kill intensified. At the Throne, Toriel and Asgore asked the Six Human Souls to help stop him, and the souls began to glow.

• Ye Yu repeatedly slashed Scarlet, but her ghostly form reassembled after each attack.
• The Subsystem showed Ye Yu the word “Determination,” and after studying the power in the Void Space, he reloaded and used it to restrain Scarlet’s true form.
• Scarlet told Ye Yu that she had been buying time for Captain Undyne to arrive, then Ye Yu crushed her ghostly form and left her doll lifeless.
• Ye Yu’s LOVE rose to LV 10, and he prepared to continue slaughtering monsters in New Home as fierce winds erupted around him.
• At the Throne, Asgore opened the containers holding the Six Human Souls, and Toriel pleaded with them to help destroy Ye Yu.
• The Six Human Souls shimmered and began rising from their containers.

Undyne transformed and attacked Ye Yu with an overwhelming barrage of spears, killing him before he used Load to rewind time. Ye Yu survived the next attack briefly by charging his blade, but Undyne threw him hard, while Linde sat behind the Throne as a darker aura gathered around his hidden hand.

• Undyne appeared on the rooftop and entered her determination form, filling the sky with spears.
• Undyne sent a physical spear barrage at Ye Yu, and the attacks passed through his defenses and killed him.
• Ye Yu used Load to rewind time, and Undyne sensed the change but resolved to keep fighting.
• Ye Yu charged his blade and destroyed much of Undyne's spear barrage before blocking her surprise kick.
• Undyne grabbed Ye Yu's wrist and threw him, leaving him focused on surviving until her transformation ended.
• Linde sat in a locked room behind the Throne as a darker aura formed around his hidden hand.

Linde created a flaming greatsword Spell Card and gave it to Undyne, who used it against Ye Yu during their battle. Ye Yu died to her attack, blamed Linde for the strange changes in the world, and continued the fight.

• Linde fused a flaming greatsword into a Spell Card after accidentally triggering a reload during his experiment.
• Linde planned to give the weapon to Undyne and added spherical and diamond-shaped bullets to it.
• Ye Yu survived Undyne’s changing attack patterns for nearly ten minutes before she used the Spell Card to summon the flaming greatsword.
• Undyne unleashed a dense barrage of bullets and then swept the flaming sword at Ye Yu, killing him.
• Ye Yu blamed Linde for altering the monsters’ abilities and vowed to kill him before pressing Continue.

Ye Yu defeated Gaster’s four followers after Monster Kid intervened to save Undyne and transformed into Dead Monster Kid. The victory raised Ye Yu’s LOVE to 12, while the Subsystem fell dormant after empowering his Erasure Knife.

• Ye Yu struck at Undyne, but Monster Kid took the blow and helped teleport her away.
• Monster Kid transformed into Dead Monster Kid and joined Gaster’s other three followers to confront Ye Yu.
• The Subsystem strengthened Ye Yu’s Erasure Knife at the cost of falling dormant.
• Ye Yu dodged the followers’ attacks and struck all four with an invisible slash.
• Ye Yu defeated the followers, gained 3600 EXP and 576 G, and increased his LOVE to 12.

Linde created a spell card that let Undyne make three copies of herself while Frisk remained locked up. Meanwhile, Ceroba, North Star, and Martlet reunited to face Ye Yu, who had nearly killed Martlet, and the chapter ended with the three preparing to fight him.

• Undyne found Frisk and Linde in the room, then helped Linde test a spell card using her Determination Form.
• Linde created Forbidden: Quadruple Existence, a card that let Undyne control three copies of herself for ten minutes.
• Ceroba led North Star through the alleys to meet an old friend as Ye Yu hunted them down.
• Ye Yu struck Martlet with his blade, and Ceroba arrived as Martlet recognized that Ye Yu was human.
• Ceroba injected Martlet with the completed Boss Serum, transforming herself into a nine-tailed fox and Martlet into a blue bird of determination.
• North Star took out a Gatling gun, and the three prepared to face Ye Yu together.

Ye Yu continued his massacre of monsters from the yellow soul period, growing stronger as his LOVE rose. Mettaton NEO confronted him with her reinforced body and attacked from the air, while Linde decided to send Ceroba's Spell Card to Sans.

• Ye Yu killed North Star before he could fire his Gatling gun, raising his LOVE to 15.
• Martlet and Ceroba accepted that Ye Yu would eventually defeat them as he charged through their attacks.
• Linde learned from Chara that Ye Yu had killed the monsters from the yellow soul period and chose to give the Spell Card to Sans.
• Axis self-destructed and left Ye Yu with barely any health, raising his LOVE to 17.
• Ye Yu struck Mettaton NEO, but her steel body withstood the blow, and she flew into the sky and bombarded him with weapons and robots.

Linde and Frisk tried to stay cheerful while Ye Yu continued killing monsters, defeated Mettaton, and fought Sans through repeated reloads. Sans unleashed a modified ice-spell barrage, and the Subsystem awakened as Ye Yu faced the attack.

• Linde reassured Frisk that the dead might return after a reload, then played a game with them while Flowey watched.
• Ye Yu defeated Mettaton after a prolonged battle, and her self-destruction left him at nearly zero HP before determination revived him.
• Alphys told Gaster that they had collected almost enough data, while Ye Yu destroyed the mechanical guards sent against him.
• Sans confronted Ye Yu and killed him with a physical bone attack; after Ye Yu reloaded, Sans fought him repeatedly as Ye Yu learned his attack patterns.
• Sans used Linde's modified Icefall and Diamond Storm spell card, trapping Ye Yu in a dense barrage just as the Subsystem awakened.

The Subsystem altered Ye Yu’s hitbox to help him survive the skeletons’ assault, but Sans, Papyrus, and Semi fought him together until Semi sacrificed himself to empower Sans and Papyrus. Papyrus ultimately fell to Ye Yu’s delayed Guaranteed-Hit Slash, raising Ye Yu’s LOVE to 21.

• The Subsystem burned its remaining power to shrink Ye Yu’s hitbox, allowing him to survive Sans’s attacks and reach him before Papyrus and Semi intervened.
• Sans, Papyrus, and Semi coordinated their bone barrages against Ye Yu, who learned to dodge their attacks and wounded Semi’s Chainmail.
• Ye Yu used a feint and teleportation to attack Papyrus, but Semi shielded his grandson and turned into Garbled Code that entered Sans.
• Semi explained the Interlayer World to Sans, then helped him return to the Surface World and join Papyrus, granting Papyrus their powers.
• Papyrus combined Blue Bones and Orange Bones to fight Ye Yu, but Ye Yu’s delayed Guaranteed-Hit Slash struck him and dissipated Papyrus, Sans, and Semi.
• Ye Yu’s LOVE rose to 21.

Ye Yu fought his way through the monsters and the defenders in the Last Corridor, gaining enough LOVE to reach the Throne. Asgore absorbed the Six Human Souls and prepared to face Ye Yu alongside Toriel.

• Linde woke from a dream he could not remember, while Ye Yu began fighting Gorson in the Last Corridor.
• Rudy's family, a young dragon, and the surviving monsters joined the battle, but Ye Yu killed them and raised his LOVE to 23.
• Undyne summoned duplicates and fought beside Gorson, while Alphys and Gaster deployed a giant robot; Ye Yu bypassed its defenses and killed both defenders, reaching LOVE 24.
• Asgore absorbed the Six Human Souls, and Toriel agreed to fight without holding back despite Asgore's inability to manipulate time.
• Ye Yu reached the Throne, where Asgore and Toriel waited, while Flowey burrowed underground to stay safe.

Ye Yu fought Asgore and Toriel, growing stronger as he endured their attacks and eventually landing a devastating slash on Asgore. Asgore survived as a Demigod and unleashed a world-shattering aura, while Frisk and Linde prepared nearby.

• Asgore and Toriel attacked Ye Yu, who repeatedly dodged and blocked their magic and weapons while reloading his save after being struck.
• Ye Yu’s concentration sharpened, and he found an opening in Asgore’s defense, forcing Asgore back despite his quick parry.
• Toriel’s spell pushed Ye Yu’s inner energy past a threshold, and its eruption cleared the surrounding projectiles.
• Ye Yu’s slash severed Asgore’s trident and hit him for 9999999 damage, but Asgore stood back up and told Toriel to find the two children.
• An invisible force stopped Toriel from leaving as Asgore awakened his Demigod power and overwhelmed Ye Yu with his aura.
• Linde warned Frisk that Ye Yu had arrived, while Frisk announced that Linde had lost their game of four in a row.

Ye Yu escaped Asgore’s illusionary world and killed Toriel before Asgore could stop him. Asgore eventually turned to dust, the six human souls were destroyed by Ye Yu’s subsystem, and Ye Yu approached the Throne room for the final battle.

• Asgore drew Ye Yu into a sunlit world shaped by his hopes, but Ye Yu ignored the illusions and escaped by cutting open a rift.
• Asgore returned to the Underground too late to save Toriel, whom Ye Yu had killed.
• Asgore fought Ye Yu until his altered form expired, then turned to dust, leaving one monster soul and six human souls behind.
• Flowey tried to seize the six human souls as Ye Yu reached for them, but the subsystem destroyed them and raised Ye Yu’s LOVE to 25.
• Ye Yu approached the room behind the Throne and heard two children arguing over a game.

Ye Yu fought Linde and Frisk in the Underground, but Chara took control of Frisk and helped Linde repeatedly force him to reload. Their battle reached the Judgment Corridor, where Linde’s modified Dream Seal struck Ye Yu with homing orbs and sent him back into another reload.

• Ye Yu found Linde and Frisk in a locked room and attacked, but their Haste let them dodge and hit his abdomen.
• Linde and Frisk used Forbidden: Quadruple Existence to create copies of themselves and overwhelm Ye Yu until he reloaded.
• Chara took control of Frisk, struck Ye Yu with the True Knife, and caused another reload.
• Linde and Frisk continued fighting Ye Yu as they moved into the Judgment Corridor, where Linde’s ice Spell Card failed to hit him.
• Linde used Modified Dream Seal, and its homing orbs struck Ye Yu and sent him into another reload.

Ye Yu endured Linde and Chara’s attacks until Linde exhausted his Spell Cards, but Linde then merged his soul with Frisk’s to create Fried. Fried activated Fantasy Nature and revealed a deadly attack that pursued Ye Yu into Void Space before the void swallowed it.

• Ye Yu countered Dream Seal and struck Linde and Chara with a shock wave, then dodged Linde’s slash and endured Hidden · Breezy Cherry Blossom.
• Flowey returned the Eight Trigram Furnace to Linde, who used it to fire Magicannon Spark at Ye Yu.
• After Ye Yu survived Linde’s Spell Cards, he defeated Linde, whose soul merged with Frisk’s soul.
• Fried activated Fantasy Nature and used a death character from her keyboard to unleash annihilating power at Ye Yu.
• The attack followed Ye Yu into Void Space, where the void swallowed it, and Ye Yu pressed load.

Fried fought Ye Yu while waiting for Flowey to bring determination, then injected herself with all ten syringes in an attempt to seize control of the timeline. The final injection triggered a successful Load as her body began to collapse and Ye Yu attacked.

• Fried and Chara fought Ye Yu in turns, and Fried unleashed Fantasy Nature and the Eight Trigram Furnace's Super-Ultimate Spark, but Ye Yu repeatedly reloaded and survived.
• Flowey arrived with a briefcase of determination gathered by Alphys, and Fried began injecting herself while Flowey restrained Ye Yu with vines.
• Fried injected the seventh syringe and began dissolving as her body struggled to withstand the determination.
• Ye Yu broke free and slashed at Fried, who injected the final syringe.
• A message appeared stating that Load had succeeded.

Linde restored Ye Yu’s emotions and explained why monsters sought peace with humans, then discovered Ye Yu came from a similar version of his world. They reached the Ruins, where Frisk beat Linde for upsetting her, and Toriel’s return finally interrupted the fight.

• Linde and Frisk restored Ye Yu’s emotions, and Ye Yu questioned whether monsters could coexist peacefully with humans.
• Linde explained that monsters were beings of thoughts and feelings, then used old-world references to confirm that Ye Yu shared a world similar to his own.
• Linde told Ye Yu that a god-level being had used him to preserve its desired cycle, and Ye Yu agreed to join Linde against it.
• Linde explained Undertale’s story to Ye Yu as they walked to [Home] in the Ruins, where Frisk waited angrily for them.
• Frisk threw Linde to the ground and punched him repeatedly, and Toriel’s return from the Royal Capital brought the beating to an end.

Ye Yu marveled at the monsters' forgiveness while Linde gave up trying to stop the coming disaster and spent his remaining day exploring with Frisk. They visited the Ruins and Snowdin, sharing music and stories before continuing their journey through the Underground.

• Ye Yu confessed his crimes to the monsters, who forgave him, while Toby told Linde that one day remained.
• Linde chose to spend his final day with Frisk, and Ye Yu stayed behind to do something on his own.
• Linde and Frisk visited Asgore and Toriel in the Ruins, then listened as Napstablook and Dalv performed their song, "Star."
• Frisk described the surface to a crowd of curious monsters, and Linde reflected on the world's history and development.
• In Snowdin Forest, Linde and Frisk reassured the snowman that its piece of snow had traveled across the western Underground and built a snowman of Frisk.
• Linde and Frisk found Martlet's cabin empty and continued through the forest into Snowdin.

Linde and Frisk visited the Bone House, where they discovered Papyrus had learned to cook good spaghetti from Semi. Semi then told Linde about an Artifact hidden in Waterfall, prompting Linde to decide to investigate it later.

• Monster Kid accidentally knocked Linde down in Snowdin, and Sans invited Linde and Frisk to the Bone House.
• Papyrus served Linde and Frisk his improved spaghetti, which both children enjoyed.
• Sans explained that Semi had taught Papyrus to cook after nearly passing out from his earlier spaghetti.
• Frisk played chess with Semi while Linde asked why they had been summoned.
• Semi told Linde that an Artifact lay hidden in Waterfall, and Linde decided to look for it later.

Player explained to Ink Sans why Toby had Linde enter the Main Universe and how the Error-Checking System was trying to restore the universe as a game. Error Sans joined them to watch the battle after Ink Sans stopped him from fleeing.

• Ink Sans asked Player why Toby had wanted him to send Linde into the Main Universe, and Player explained that Linde’s arrival created new possibilities and changed the universe’s nature.
• Player said the Error-Checking System retained its power because Ye Yu’s presence made the universe mistakenly believe it was still a game, and it planned to reboot the universe and erase Linde and Ye Yu.
• Ink Sans recalled that Linde had once been driven out, and Player explained that Toby had fought the Error-Checking System while Player rescued Linde.
• Error Sans arrived, accused Ink Sans of creating more multiverses, then recognized the creator god’s power and tried to flee.
• Ink Sans grabbed Error Sans and persuaded him to stay and watch the battle with them.

After a narrow chess victory over Grandpa Semi, Frisk and Linde visited Waterfall and Hotland before heading back to the Royal Capital. Linde prompted Mettaton to remember Napstablook, and Mettaton rushed off to find his old friend.

• Frisk won a chess match against Grandpa Semi, then she and Linde set off to visit the Artifact after having some fun.
• Angry Dummy confronted Frisk over scaring their cousin in the Ruins, but Linde's remark helped the dummy fuse completely with its body.
• Frisk and Linde found Alphys and Gaster modifying the Gaster Shock Cannon, then left without disturbing them.
• At the Mettaton Resort, Linde reminded Mettaton of Napstablook, and Mettaton flew off toward his former home in Waterfall.
• Linde collected the food from the table, and he and Frisk took the elevator to the Royal Capital.

Linde and Frisk found the red time core, while Toby used it to send them into the past and free the Universe from the Error-Checking System. Ye Yu helped stop the system, survived its attack, and was offered a choice between returning to his original Universe and staying with the monsters.

• Linde and Frisk visited the Barrier, then opened the great door in Waterfall by playing "His Theme" and found the red time core.
• Toby returned and powered the time core, intending to send Linde and Frisk to a time before the Error-Checking System existed.
• Ye Yu and the monsters gathered in Waterfall to defend Linde and Frisk, and Ye Yu used their power and the Six Souls to fight the Error-Checking System.
• Ye Yu returned the souls inside him to avoid the system's rule-based attack, buying enough time for Linde and Frisk to vanish into the past.
• Toby destroyed the Error-Checking System, and its game-related powers and manifestations disappeared.
• Toby restored Ye Yu as a normal human and asked whether he wanted to return to his original Universe; Ye Yu began to give his answer.