@HorsesandMuchMOAR
810 can be splitted into “8” and “10”, and actually spelt “や” and “じゅう”. “やじゅう(野獣)” means “beast”, a meme from a porn series “真夏の夜の淫夢 (A Midsummer Night’s Lewd Dream)”, which in episode 4 the main character “Tadokoro Kōji (田所浩二)” was nicknamed “beast senior (野獣先輩)”. You can find some pics of it on Derpibooru.
Also, the full version of “810” is “114514, 1919810” (“いいよ！来いよ！行く行く野獣！”, Go on! Come! Go go Beast!)
810 can be splitted into “8” and “10”, and actually spelt “や” and “じゅう”. “やじゅう(野獣)” means “beast”, a meme from a porn series “真夏の夜の淫夢 (A Midsummer Night’s Lewd Dream)”, which in episode 4 the main character “Tadokoro Kōji (田所浩二)” was nicknamed “beast senior (野獣先輩)”. You can find some pics of it on Derpibooru.
Also, the full version of “810” is “114514, 1919810” (“いいよ！来いよ！行く行く野獣！”, Go on! Come! Go go Beast!)
Edited
I thought I was the one responsible because something I’d done had ended up with there being 810 years between G4 and G5…
Yep. It was part of my “immortality birthday cards” edit series.
810 is a number used in Japanese websites as a meme mocking American wrestlers like Billy Herrington.