ALRIGHT,today I'm gonna tell you about a theory for JSHK/TBHK
For Chapter 78,We saw that tsukasa kun (my Lovely and cute tsukasa,I'm gonna die just drowning at my own tears) sacrifice himself for amane who was deeply ill and from what the doctor said amane wouldn't be able to survive to a month,so tsukasa made a pact of the ghost at the red house,that he will sacrifice himself for his brother as long as THEY will grant his wish. That was To heal amane. And maybe then,in the few years, amane will learn his brothers sacrifice and blame himself,but he ended up dying ( I still can't match all pieces together like when amane had too much bruises and all )
Just reply on what you think about this theory