In Japan, it's polite to use honorifics to describe your relationship to another person.
Kun refers to a close person or partner.
I think chan refers to a friend.
Senpai refers to a lover I think.
Not 100% sure about all of them. Anyone can correct me if I'm wrong. It's used a lot in anime, and the group was completely composed of weeaboos.
English
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Ew anime sorry
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It's fine. Some love it. Some hate it.