
Quick answer — Keitarou Takahashi worked on Jormungand: Perfect Order (Original Creator), Fate/Grand Order Final Singularity - Grand Temple of Time: Solomon (Original Character Design), Jormungand (Original Creator).
Keitarou Takahashi worked on Jormungand: Perfect Order (Original Creator), Fate/Grand Order Final Singularity - Grand Temple of Time: Solomon (Original Character Design), Jormungand (Original Creator).