Board Thread:General Discussion/@comment-82.43.138.194-20140707202022/@comment-24822455-20140717003918

Wikipedia list Japan having a marriageable age of 20. 18 for males and 16 for females with parental consent. (I know nothing personally of Japan marrage laws, so that's all I can post)

That would put Kazuto, as the younger (Kazuto being the youngest, and needing to be the oldest) about 4 months short of 18. I would assume at this point, all parents would approve, though Asuna's mother might drag he feet a bit.

Also, ALO currently doesn't have a in game marriage system.