A computer genius and hacker that lives in a secret room of Izumo Inn, and was once mistaken for a ghost by Kusano. She becomes Minato's third Sekirei. She also likes to shorten people's names and substitute tan for san.

Matsu uses a vast network of satellites and spying devices to gather large amounts of information and has even succeeded in hacking the MBI mainframe computer. She refers to herself as the 'Wisdom' Sekirei. However, despite her high intellect, she is very perverse - she uses her resources to peep on people and often tries to 'experiment' with Minato and so most call her the 'Shameless' Sekirei.

Matsu serves primarily as Minato's unofficial 'strategist', rarely venturing outside of the Inn and using her vast network of information to aid him.

Matsu has the power to access and analyze any electronic device on a telepathic level, but does not have the power to control them. Her name means a "pine" literally.

Miya's nickname for Matsu is "Hentai-Glasses".