Renshi is a Japanese instructor title used in karate and other martial arts. The word translates as «polished master» or «prepared mentor.»

The title of renshi is typically awarded to experienced instructors who have a high technical level and a substantial record of teaching students.

A renshi must:
— master Kyokushin technique;
— understand the philosophy of the school;
— uphold discipline;
— serve as an example for students.

In many Kyokushin organizations, the renshi title is awarded to masters of 5th-6th dan. It is an important step before higher ranks such as hanshi.

For karateka, receiving the renshi title represents recognition of their teaching level and experience.