Saira

Saira is a planet known for a race of giants who exist in a world larger than the world of most beings. It is the home-world of Sairagin, a grade schooler bribed by Galactic Merchant Dongoros into coming to Earth to briefly assist Zone until his true nature and intent is discovered by Kazumi Hoshikawa and he returns home after gaining math tutoring from FivePink.

Gunther briefly comes to this planet to test out "his" new mecha, Star Five, defeating Sairagin while finding out about Fiveman on Earth in the process.