[@KatherinWinter]
String but not superhuman strong

Both him and his brother trained and part of training was weight lifting

Jasper can lift around...300 pounds not with ease but he can lift it

Hachi has leaner muscle that allows him to not be as bulky but still lift around the same.

I'm not totally familiar with how much weight would be considered superhuman but 300 sounds okay to me because like I said not with ease.