Simply by listening to Tanjiro explain breathing and watching him perform the Dance of the Fire God a few times, he had comprehended Sun Breathing.
Previously, that would have been utterly impossible for Su Mu.
The last time he learned Hiten Mitsurugi-ryu, he had put in a great deal of effort. Even with Kenshin Himura personally instructing him and sparring with him countless times, he had only barely gained a grasp of it.
Involuntarily, he turned his attention to the almost unchanging Character Panel deep within his mind.
Name: Su Mu. Race: Demon. Lifespan: Infinite. Abilities: Immortal Body (complete), Super Regeneration, Physical Prowess. Weaknesses: None. Status: Perfect. Blood Demon Art: Devour (perfectly acquire the target's talents, abilities, and Blood Demon Art). Swordsmanship: Hiten Mitsurugi-ryu. Breathing Style: Sun Breathing. Constitution: 3.1 (a normal adult's constitution is 1). Agility: 3.2 (a normal adult's agility is 1). Strength: 3.1 (a normal adult's strength is 1). Spirit: 5.5 (a normal adult's spirit is 1).
Now, after so long, his previously unchanging Character Panel had changed again. There was a new Breathing Style field, with Sun Breathing listed under it.
Although the Character Panel in his mind served little purpose, it accurately reflected his condition.
Now that Sun Breathing had appeared on it, that proved he really had comprehended Sun Breathing. It was not his imagination.
Clearly, his sudden ability to do what he could not do before was connected to his having consumed the Blue Spider Lily and evolved into a Perfect Life.
Sure enough, evolving into a perfect life-form had not merely allowed him to overcome his weakness to sunlight and control his flesh-and-blood cravings.
Even his talent and comprehension might have improved greatly. Those changes were simply latent and difficult to notice.
Had he not comprehended Sun Breathing so quickly