I had a fleeting thought a long while back and I dismissed it because the math is all wrong, but it just came back to me: What if Takeda is the Small Giant?
Parents divorced and now he has his mother’s maiden name; possibly lost his memory in an accident or wishes to remain anonymous, etc. , etc.. But of course not, because he’s older than Saeko and would not have been out of high school long enough to become a teacher.
However, I’m still stuck on the catalyst idea that made me consider that in the first place: Why is the Small Giant such a mysterious figure? What happened to him? Is he still playing volleyball? Why is he always in shadow like he’s a final boss?
Ushijima was in shadow for a while because he’s like a boss that needs to be beaten before they advance to Nekoma who is the final boss. On the other hand, I guess the Small Giant is kind of a final boss, if only for Hinata alone.
But still, why so mysterious?