2-dome no Jinsei, to Omottara, Jitsu wa 3-dome Datta ~Rekishi Chishiki to Naisei Doryoku de Fukou na Rekishi no Kaihen ni Idomimasu~ - Vol. 2 Ch. 6

[MangaDex]

 

[Romisterie]

If only he knew that they are already suspecting him to have precognition skill so revealing it will be believed

 

[Psychronia]

I mean...that was the logical conclusion to begin with. His big bro has a talent for battle, so cultivating it with a guy even more talented in battle makes sense.

Not to mention it can save his bro from his death flag too.