is the twenty sixth chapter and the second chapter in volume eight of Nana
It's chapter where Hachiko gets to know that she is really pregnant and gets echography of her baby.
Nana O. and Nana K. hear from Misato that Shin grew up in foreign country and not even sure if both of his biological parents are japanese.
Shin overhears conversation of Takafumi Kawano and Matsuo, where Matsuo express a lot of doubts about ability of Blast to gain success in sales, if they'll debut.
Takumi finds out that Hachiko is pregnant and calls Nobu (and Nana O. hears what happened too).