Ever since Yanbai had lovingly "corrected" him countless times, Tobirama Senju had kept his distance from him.
At first, Tobirama Senju had simply thought Yanbai found him annoying, so he tried not to show up in front of him and make a nuisance of himself.
Even so, Tobirama Senju still paid more attention to Yanbai's affairs than anyone else did.
Yanbai caused far too much trouble for Tobirama Senju to leave him unsupervised.
What comforted Tobirama Senju was that, although Yanbai seemed to dislike him intensely, he always made time to give him "treatment" every day.
The "treatment" that Hashirama Senju had once avoided like the plague was the only thing that let Tobirama Senju feel Yanbai's familial affection for him.
Tobirama Senju knew Yanbai loved animals, so he tried to stay on good terms with them.
Tobirama Senju was clever and levelheaded. He could tell that the animals close to Yanbai were all unusually intelligent.
Whether they were birds that often flew beneath the eaves, hens in the coop, dogs guarding the house, or stray cats roaming around the Clan Grounds, every one of them was Yanbai's friend.
The clan took very good care of the two hens that often played with Yanbai.
And yet... that still wasn't enough.
Tobirama Senju could only watch Yanbai from afar, with no way of learning more about him.
Tobirama Senju began researching escape Ninjutsu that could counter Yanbai's beatings, Ninjutsu that could counter the Uchiha Clan's Fire Release, and unusually intelligent animals...
Tobirama Senju made a bold attempt. He caught a rat that seemed unusually intelligent and used a red-hot, cherry-blossom-shaped branding iron to burn a cherry blossom onto its rear.
For that rat, this was horrific torture.
Not only that, Tobirama Senju also tied thread around the rat's front teeth and tethered it beneath the cherry blossom tree in the courtyard.
Sure enough, the rat cursed up a storm.
Yanbai took pity on it and healed it, then even fattened it up.
Once its wound healed and it grew plump, the cherry blossom on its rear grew bigger too.
After that, Tobirama Senju set his sights on this rat.
The birds kept in the Clan Grounds rarely left, and neither did the cats and dogs.
At first, Tobirama Senju had focused on wild birds.
But after catching a few, Tobirama Senju discovered that birds were too fragile and difficult to keep.
They often frightened themselves to death.
Birds scared themselves to death easily, were hard to track in flight, and were easily noticed if there was anything unusual about them.
So Tobirama Senju chose a rat as his intermediary.
Tobirama Senju personally picked out an unusually intelligent rat and delivered it to Yanbai.
That was the very rat Yanbai had named Cherry Ink. Its "distinguishing feature" was obvious, making it easy to track.
Tobirama Senju didn't need to follow Yanbai. He only needed to follow Cherry Ink to learn some of Yanbai's secrets.
And hadn't he... done just that?
Some time ago, Cherry Ink had disappeared. Tobirama Senju had thought that after Yanbai sent it out to play, some wild beast had eaten it.
But the rat turned out to be coming back every few days.
At the time, Tobirama Senju had thought that perhaps the little fellow had gone off to stake out a forest territory, find a mate, and have babies. Rather than trouble Yanbai with all that in the Senju Clan, it had settled outside.
Still, Tobirama Senju was cautious, so he followed Cherry Ink anyway.
To Tobirama Senju's surprise, the rat's... new home was actually in the Uchiha Clan's Clan Grounds.
That in itself was nothing. Tobirama Senju had always believed Yanbai had strong opinions and ideas of his own. Sending a rat to infiltrate the enemy was an excellent idea.
They could gather intelligence on the Uchiha Clan through this rat.
At the same time, the rat could eat the Uchiha Clan's food and save the Senju Clan's supplies.
So Tobirama Senju let it be and kept watching.
Until today...
Tobirama Senju saw the rat sneaking off with food Yanbai had given it.
Tobirama Senju was utterly baffled. If the rat had already moved to the Uchiha Clan, why did it keep coming back for handouts?
Something was very wrong!
So Tobirama Senju followed it.
And so Tobirama Senju discovered Yanbai's secret.
Long after Madara Uchiha and Uchiha Izuna had disappeared from view, Tobirama Senju suddenly raised a hand to cover his face. His formerly composed expression gradually twisted into a grimace.
His blood-red eyes filled with a sinister glare that showed through the gaps between his fingers.
Tobirama Senju refused to believe his beloved younger sister had betrayed the Senju Clan. He believed that not only he himself, but his father and even everyone in the Senju Clan would refuse to believe Yanbai would betray them.
But that Uchiha boy had Yanbai's clothes. Yanbai must have given them to him willingly, yet he didn't seem to cherish them.
Not only that, Yanbai had even sent that fat rat to deliver food to the boy.
How could anything so foolish happen in this world?
Everything made it look as though his younger sister's affection was entirely one-sided, and that enraged Tobirama Senju.
Yanbai must have been deceived, right?
It was all the fault of the evil Uchiha Clan...
Father mustn't find out about this. Despite the fury in his heart, the rational part of Tobirama Senju's mind remained exceptionally clear.
Tobirama Senju had previously chosen to watch from afar precisely because he didn't want his relationship with Yanbai to become too strained.
The same held true now.
Tobirama Senju punched the tree trunk beside him, and cracks instantly spread across it.
His expression was icy, his chest heaving. He had to hold himself back.
He had to think of a foolproof solution.
He couldn't interfere by force. That would only push Yanbai further and further away, just as it had before.
Then... what should I do?
Tobirama Senju sank into deep thought.
Before you continue