KNIGHT'S & MAGIC

A Japanese mecha otaku dies in a car accident and his soul is reincarnated into another world as Ernesti Echevarria. Eru inherits memories and interests from his previous life, and aims to be a pilot of a Silhouette Knight, a large humanoid weapon that really exists in his world.(Source: Anime News Network) — Description from AniList community (anilist.co).