Roh594
Honestly, 2 or 3. If he travels in the future by an artifact, it's fine. But looking at his age, it would be weird if it's just time passing.
I'd say Yu Yan.. as all the ones listed on this page are basically little kids to the mc..
Xiao Ninger
If theres the way I wold put my vote in Yu Yan, without beating an eye.
how about mythology phanteon which he summoned from another universe?
