Takahiro Matsui was a detective with the Tokyo Metropolitan Police. He appears to be one of Captain Gotos Kiichi Goto few trusted friends. Matsui first contacts Unit 2 to Investigate a monster, and was involved with them from that point on. Matsui also appears to keep Goto informed with things going on in the police force. Matsui is a traditional investigator and prefers to do his investigating on foot, rather than drive around. Goto depended on him when things got complicated, such as missing persons cases and crazy computer programmers that SV2 Section 2 came in contact with.
He plays a key role in the Patlabor Movie, when Goto asks him to investigate Eiichi Hoba.