Where did u read dat?
And btw hisako (the woman throwing up) is yuki's aunt and she never met his mother yet.
There is a zero possibility for this theory. Tetsu is older than Yuki or at least they're the same age. In this flasback Yuki is already a little kid! So please quit writing nonsense.
No your wrong, yuki is older than tetsu. And because she was prego they kept tetsu in the dark about it. Yuki is tetsu cousin since the guy with scar is his uncle. And another spoiler, the chinese guy is going to use jun to get back yuki.
I'm pretty sure tetsu is older than yuki, based on the flashbacks yuki is 16 or 17 and tetsu is 17 or 18.
Spoiler the woman throwing up is yukis friend mom. Tetsu. She is prego with tetsu, so tetsu is yakuza son. :)