Ultraman: I Rebooted Time and Space, Giving Everyone a Perfect Ending

Ultraman Stories, All With a System

Anything Ultraman-related, but it has to have a System.

This Is a Robbery. Hand Over Your Ultraman Fanfiction

Looking for Ultraman Fanfiction: No Saintly Leads, One or Multiple Love Interests Are Fine

Looking for books similar to Ultraman: Humanity Betrays Me? I Choose Darkness Instead.

Ultraman as the Protagonist, No System, No Female Lead, No System!!!

Monsters are fine too, but preferably no Reionics. The protagonists who are Reionics are all too overpowered, and their monsters grow way too fast. Most importantly, they have an absurd number of them. No more relying solely on the bond to kill off one generation after another, and no Tiga.

Ultraman

Books about Ultraman Seven X, Ultraman Zero, Ultraman Tiga, Agul, Ultraman Geed, Ultraman Belial, Tregear, Ultraman Saga (crossed out), Ultraman Orb, Ultraman Gruebe, Ultraman Taiga, Ultraman Titus, Ultraman Great, Ultraman Powered, Ultraman Ribut, Hikari, Ultraman Justice, Ultraman Cosmos, Ultraman Legend, and others.