Arion  

Neo Heroic Fantasia Arion, Арион, アリオン, ネオ・ヒロイック・ファンタジア アリオン, ネオ・ヒロイック・ファンタジア　アリオン

The story you're referring to is a mythological tale from Greek literature. It tells of Arion, a warrior trained by Hades in the Underworld for revenge against Zeus. He was told that his mother Demeter's blindness was caused by Zeus and that her sight would be restored upon Zeus' death. After completing his training, Arion left the Underworld with Geedo, a friend he had made during his time there. However, on their way out, Seneca stole Arion's sword, leading to his first encounter with forces of Zeus commanded by Athena. He was captured but later released by Lesfeena, one of Athenas serving girls. As Arion rejoined Geedo and Seneca, the battle between forces of Zeus and Poseidon took place in the background, while Hades sat quietly and Apollon seemed to have his own plans.