Jo-Jizaiou Bosatsu One of the 25 bodhisattvas, he is a bodhisattva with the virtue of unobstructedness, who gathers his mind in one place and does not scatter or become disoriented, changing and reborn freely without any disturbance.
Mugai means "unobstructed light" because it is not obstructed by anything and is one of the twelve lights emanating from Amida Buddha.
As it refers to the light of salvation, he is considered one of the bodhisattvas who come to welcome Amida Buddha as his attendant tribe.