Karashi Nerimaya is a university student and a two-time champion of the student rakugo competition known as the Karaku Cup. After the events of the Karaku Cup Arc, he enters the Sanmeitei School and adopts the new name Karashi Sanmeitei. He achieves the distinction of being the first and only rakugoka to reach the final round of the Z-1 Grand Prix.

His surname, Nerimaya, combines the characters for "practice," "polish," and "house" or "expert."

Karashi is a tall, slender young man with black hair and dark eyes, frequently depicted with a confident, smug-like grin. Outside his performance attire, he often wears a formal shirt featuring a branch pattern.

He carries himself with notable confidence, which at times borders on superiority—a demeanor amplified by his repeated success in the Karaku Cup. A skilled performer, he prides himself on revitalizing classic rakugo tales for contemporary listeners, though his self-assurance can occasionally be perceived as arrogance. He serves as a primary rival to another character and, despite his know-it-all attitude, comes to acknowledge his own limitations after witnessing a particular rakugo performance.

His approach to rakugo involves modernizing traditional stories by infusing them with personal experiences, all while preserving the core of the original narrative. Another character has likened this style to something approaching stand-up comedy.

Karashi’s interest in rakugo sparked during university after joining a rakugo club. Finding the conventional stories dull and unengaging, he developed his own contemporary method of performance.

Having won the Karaku Cup twice, he attracted offers from several major companies. He ultimately chose to join the Sanmeitei school, where he became a student of Enso.