The Gridman Alliance (グリッドマン同盟 Guriddoman Dōmei) is an unofficial team in SSSS.GRIDMAN, who are most involved with Gridman and the only ones not affected by the aftermath of the attacking kaiju. Their "base of operations" is in the Junk Shop owned by Rikka's mother.
Yuta Hibiki (響裕太 Hibiki Yūta) is Gridman's partner and the one who transforms into Gridman to fight the kaiju. Later on, he figures out that he is actually a part of Gridman which explains why he has no memories, and the real Yuta is lying dormant.
Rikka Takarada (宝多六花 Takarada Rikka) is the unofficial co-owner of the Junk Shop, where Gridman resides. Despite being apprehensive about Gridman Alliance at first, she develops a strong determination to help Yuta fight kaiju in order to protect her loved ones.
Sho Utsumi (内海 将 Utsumi Shō) is the founder of the Gridman Alliance. His knowledge about the Ultraman Series and its various tropes makes him an unlikely asset to the team.
- Junk (ジャンク Janku): An old computer sitting in the Junk Shop. Gridman resides within this computer.