The Trash Returned from Warhammer

Shinji Ikari awakens in Neo Tokyo-2 with his memories and iron will as a Space Marine Librarian who served the Imperium for a century. When a letter arrives from his estranged father, Gendo Ikari, summoning him to Neo Tokyo-3, Shinji ignores his past traumas. Instead, he interprets the summons as a holy mission from the God-Emperor. The former Astartes sets out to defend humanity once more, treating the events of Evangelion as his next theater of war. — Description from novelcodex.org