Link: Secret Mission Sennyuu Sousakan Wa Zettai Ni Ma

A perfect protagonist risks becoming a Mary Sue. The best stories using this trope introduce caveats:

The story follows (or a similar protagonist name), a skilled undercover investigator working for a covert government agency. Her mission: infiltrate a criminal organization that specializes in human trafficking, illegal arms deals, or blackmail. The title’s phrase "zettai ni makenai" (never lose) hints at her resolve despite overwhelming odds. secret mission sennyuu sousakan wa zettai ni ma link