Quick answer — Akihito Okano performed 1 anime theme, including "Hikari Are" from The Seven Deadly Sins: Dragon's Judgement.
Akihito Okano performed the anime theme songs "Hikari Are" (The Seven Deadly Sins: Dragon's Judgement).
Akihito Okano's first listed anime theme is "Hikari Are", the opening of The Seven Deadly Sins: Dragon's Judgement.