To add to what X-Virus669's comment, it's possible with age difference that they're brother and sister. But on top of that, my own theory is that Monoma is related to All For One because their quirks are so similar, think about it!

Toga's a high school student...

Yeah, she's, what, 17? And monoma was 15. That's 2 years, general age gap between siblings

yea

If you wanna talk conspiracy, hmu any time on here boi. Had Dabi figured out since he was introduced

Oke
Yea, Dabi was kinda obvious tbh

Yeah, facts, but still, I have conspiracy theories comin out my ears. Also, love the username, X virus is awesome

Yea. Thanks

I love how he ties in with Ricci Toby, I have a headcanon that his dad cheated on his mom while she was pregnant with Toby so that X and Toby are half brothers. That may or may not be canon, but still lol

oooooo

Toga's quirk allows her to transform into someone, if she gets their blood. And Monoma's quirk lets him copy anyone he touches quirk, so they can both copy things. AND they both have blonde hair and are kinda crazy