
Ta kun (?) Got divorced with his wife recently, she cheated on him and that glasses guy used to be a brother in law with him.

I think the glasses guy is his cousin or distant relatives. He said his parents divorced, he changed his surname into his mother's maide name = uke's surname = same surname, like marriged couple

Or maybe he's that woman child... probably... don't know... me myself not understand either. ┑( ̄Д  ̄)┍

They're not related. He implies that they're LIKE relatives, but they only share a surname. It's like your last name was Smith, and your friend's last name was also smith. That is all. He was happy that his mother divorced and he was able to take on the "smith" surname(in Japan, a surname will change when this sort of thing happens. If the mother remarried, he would gain yet another new surname).

They said:
"Also we are just about relatives", Takkun said and Nana agreed.
"It's my mother side of the family that has the same surname as you", they are related through Nana's mother's family side.
I can't understand a bit. Can someone explain what this story about?
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