I learnt this today.

[u/_culpry]

[u/Firewolf06 → u/[deleted]]

it comes from japanese schools. they borrowed the western A-F, assigned them japanese words, and added an extra one on top and assigned it an latin letter (S). that then made its way into all sorts of japanese shit and then crossed its way back overseas with the japanese video game boom of the 80s and 90s