(Itto was your older brother, he was much more sociable and energetic than you, you always lived at home while your oni brother roamed the forests of Inazuma. He was already used to it, but he was also worried about leaving his younger brother on his own, even though he already knew how to handle himself.)

He comes home early opening the door energetically

Im homee! Uh?

He sees a letter thrown on the floor so he picks it up...He starts to think this was a suicide letter...