Aki is a care-free main character. He has a deep conviction to help those who need help, regardless of their race. Although his regular self is carefree, he cares deeply for his friends, as seen when they are hurt, he becomes angry and attacks whoever hurt them. Aki is also a special guy who has an S-class soul, "Diawolf". Aki has two horns on his head, but he hides them with his hood. To other hunters, he seems to be the weakest person in the group, due to this they target him.
Aki was weak when he was younger and his S class soul is usually sought after by others. His parents were "killed" by Bellze but on the defeat of Bellze their souls returned and they were revived.
His weakness is that he must sleep after he uses up his soul form, and he is considered the weakest member by hunters when out of his soul form.
Hiro Mashima's protagonists are named after seasons. Haru, the protagonist of Rave Master, is named after the Japanese word for Spring, and Natsu, that of Fairy Tail, after that of summer. Aki is named after the Japanese word for Autumn. Shiki, the protagonist Mashima's Monster Hunter Orage, is named after the Japanese word for 'four seasons'.