This is the name of a character, possibly inspired by the historical figure Yagyu Jubei, which is a common trope in Japanese media for warrior or "tough" female archetypes [3]. RJ (RJ Number):

: These .zip files usually contain the game executable, character assets, or "save data" that unlocks specific outfits (like the "XL Bra" mentioned) or gallery scenes.

Because this title is niche, the "deepest" guides are typically found in the following communities: