He went to middle school around Bofurin too, so maybe he/ his parents moved there. Maybe he had plans to finish high school, before going back, but was already 1st in line for that lead position, so he had to leave earlier
parents? did he ever mentioned they're alive? can't remember. and also, i think suo got a "thing" on adults, just like how he lectured that guy from ino-something (i forgot their name )
It was never mentioned that they died, but cosidering that he's a 16 or 17 year old child in japan he (as most of them) he should still live with his parents or at least other family. And the familiy moving to that area makes the most sense to me, because a two hour train ride from and to school, starting in middle school sounds a bit much. After all those are 4 hours per day, if he really had to do that for years, he has the most tragic backstory
so did suo went to bofurin to check them out? like how strong they are whatsoever? cuz i cant think of anything else why he went there