
Quick answer — "Ketsui no Uta" by Yuiko Ōhara is the opening theme of Mushoku Tensei: Jobless Reincarnation Season 3.
"Ketsui no Uta" by Yuiko Ōhara is the opening theme of Mushoku Tensei: Jobless Reincarnation Season 3.
"Ketsui no Uta" is performed by Yuiko Ōhara.