@Aquirkypotato Well, if I can assist, I believe 4 or 3 years should do it. Depending on what age your reader is. Mine is 18-19, or really just 19, because I based each character's age by their year. First year is 19, second 20, and so on.
Because, let's be honest, those guys in Tokyo Debunker aren't high school guys. One house runs a literal casino, Rui has a bar, they drink alcohol, and with Alan's past shown as a high school student too, I can say with confidence they're all adults.