MR stands for Mugen Racing. The MR Ninja engines were made in the GRP Gandini factory along with Mario Rossi. These were made for Mugen Seiki and utilized the MR Ninja branding and were distributed by Mugen Seiki.
| Variant | |
|---|---|
| Type | Private |
| Parent Company | Mugen Seiki |
| Founded | 2006 |
| Divisions | MR Ninja |
| Headquarters | Funabashi, Chiba, Japan |
| Status | Inactive |
| Website | Click |