Sentai Red Isekai de Boukensha ni Naru

Asagaki Togo was the Red Ranger in a heroic Ranger squad. During their final battle against the ultimate evil organization, he suffers a crushing defeat and resigns himself to death... That is, until he finds himself reborn in an entirely different world! Embracing his new role as an adventurer, he transforms into Kizuna Red and continues his pursuit of justice, helping those in need. Enjoy this heroic tale of a Ranger becoming the protector of another world!

(Source: MANGA UP!)