Ikumatsu is the owner of the Hokuto Shinken (北斗心軒) ramen shop. She was first introduced when Katsura Kotarou worked undercover at her shop, due to injuries and being on the run from the Shinsengumi. 
Ikumatsu and her husband, Daigo (大吾) intended to turn their ramen shop into one that would be the best in Edo, but due to the sudden death of her husband by Jouishishi terrorists, they were unable to succeed.
Ikumatsu is blonde with dark blue eyes. Typically dressed in a pair of light grey working overalls, her ash-blonde hair is usually tied back in a ponytail while she single-handedly runs the ramen shop.
After Daigo passed away, Ikumatsu came to hold a deep grudge against the Jouishishi, as the event was one that continued to sprinkle salt onto such scars; but other than that, she is a kind, wise and deeply caring soul. Ikumatsu was quick to lend a helping hand to Katsura, even though she knew he was being chased down by the Shinsengumi, citing her reason being that the man was wounded.
Not only did she hide a fugitive in her ramen shop, but she also allowed him to work there, showing just how trusting Ikumatsu can be.
- Daigo: Her deceased husband killed by the Jouishishi.
- Nishiki Matsugoro: Her father who "abandoned" his wife and daughter.
Friends & Allies
- Sakata Gintoki: He visits her restaurant once in a while, and are on friendly terms with each other.
- Katsura Kotarou: Although she now knows that Katsura is a Jouishishi member, they are on friendly terms through the mutual acceptance of the suffering they have both endured. It is hinted by her friends that Ikumatsu might have some romantic feelings for Katsura but they are dismissed.
Her husband's brother would later come to her shop, harassing her and asking for money to run a Jouishishi group, when in fact he was just a lowly thug. After denying him the money, he would kidnap Ikumatsu and try to sell her off to a brothel. However, Katsura, who had worked as a waiter in her shop to hide from the Shinsengumi, eventually came to her rescue. They were able to thank each other before Katsura departed, still on the run from the police force.
Gintoki is known to be a frequent customer of her shop, and he comes and goes, every now and then, when he manages to have some money left after spending it on his various habits (if he had any money to begin with). During their encounter in Episode 39, it is discovered that Ikumatsu now sells soba at her ramen shop.
Katsura's subsequent television interview with Hanano Saki was carried out in Ikumatsu's ramen shop.
- Ikumatsu's name is the same as the historical geisha that hid Kogoro Katsura (the famous Japanese statesman whom Katsura Kotarou was based on) during the 1860s; she would later on become his wife.
- In the anime, when Katsura rescued her, he had untied her ropes before apologizing and leaving. In the manga though, Katsura leaves Ikumatsu still tied up when he left.
- The name of Ikumatsu's shop is an obvious nod to the martial art practiced by Kenshiro, the protagonist of Hokuto no Ken.