Zense ga Saikyou Madoushi Datta Ore, Isekai Mahou de Musou suru!

"...I remembered. I was a sage." One day, on his way home, Amahito Sakuragaku, a young man looking for work to earn money for his sister's tuition, suddenly encounters a dragon. Just as he was about to be killed, his memories of his past life as a great magician return, and he easily defeats the dragon with his awakened magic. This prompted Amahito to start working as a "slayer" who conquers dungeons. Unlike normal slayers who can only use one ability, he uses countless magic spells and achieves extraordinary results. "Wow... you're amazing, Onii-chan!" "What on earth are you...!!" A refreshing and unrivaled fantasy where you carve out your future with the magic of your past life! (Source: SB Creative, translated)