Responses
I think that it was originally translated from the fanmade Chinese version, judging by the 'Usagi-chan-sensei' nickname - 小兔老师 (which is also used in the early chapters, instead of "Usagi-san"). Basically, the translation wasn't based on the original text, so: some of the kanji characters for names and nicknames got distorted, and possibly, the person translating the names wasn't proficient enough in Japanese to get the original Japanese names right. Japanese names are a pain in the ass, as they are normally read using special readings
Rereading, and yeah I thought I was reading about someone else, but in the first few chapters, Misaki's brother is referred to as Kyoukou, not Takahiro...? And the girlfriend/fiance is Megumi and not Manami..?
Upon further rereading, Hiroki and Sumi's names are different too..?