Deimos no Hanayome: Ran no Kumikyoku
Akuma no Hanayome: Ran no Kumikyoku
Bride of Deimos
悪魔の花嫁 蘭の組曲
Two siblings were happy on Mt. Olympus, until they fell in love. Deimo's sister Venus got imprisoned in the Swamp of Death. To save Venus's life, he must find a human reincarnation so that they can continue their love.
(Source: ANN)