I found the ultimate chart:
http://www.mangago.me/read-manga/sex_pistols/mh/v06/c028.1/20/
No. In volume 7 or 8 it is confirmed he is Karen's and Makio's father's son. The chart gets updated. I have read both volumes mentioned above
you're right... I found this in french
http://i.imgur.com/t4Yoj8u.jpg
Hi sorry for the late reply i haven't been on this site in ages. Okay, you can check the most updated chart in volume 8 translated here. I have already bought them. So yeah it got confirmed probably in volume 7. i haven't read it in a while so i am not too sure ^_^
https://www.sublimemanga.com/reader/677?free_preview=1
I am confused regarding Shinobu, is he Kunimasa & Yonekuni brother or Makio's brother