my thoughts exactly!
In your number 3. Its not actually a jump, its more like a flashback of his happy time with his younger brother. And at that time maybe the pressure on him is not yet heavy and seeing his brother as his supporting place only to backfire him, I don't know maybe in psychological manner, made him today like a lazy brother. And maybe the mother at that time is not like the present, afterall high expectation really changes people ╮(￣▽￣)╭ right?
Yeah I get that's it's a flashback im not talking about his highschool life him i'm saying the jump is from his childhood with strictness to having a playful one like I was kinda going with the flow like ok he's had a paved childhood where it was only about work/school until they threw in this "younger brother" and it's like a normal happy family.. As for the mother idk they didn't show her present self but what I was talking about was all within the flashback age..
...I'm not sure how to explain it but there was definitely a jump! ヽ(`Д´)ﾉ
Σ( ￣□￣||) o-okay.... oh well, its just my opinion anyway ╮(￣▽￣)╭
1. I finished the ch so I decide to read the summery which I usually don't do and I notice the summery just spilled the beans
2. I think that Keichi after seeing that scene with the mom crying he decided to try harder to ease the load on his brother like Kazu thinks his brother is the perfect son but maybe keichi did it for him? That'd be so cute!
3. While reading I got confused for a sec.. I thought I understood the flow of the manga like OK strict parents got that but then the next scene I see them playing recklessly and the mom yells at them so I had to back track I thought it was different family lol like how do u make a jump like that!?