Ken Hisatsu is laid back, well-meaning, optimistic, and a bit negligent. Ken is a prodigy who trained by himself at the Beast Origin Village and mastered the Fierce Beast Rhinoceros-Fist, one of the oldest fighting styles in GekiJyuKen. His training has caused him to achieve a level of power that not even the Fist Saints ever attain. He grew tired of training and Bruce E.'s spirit spoke to Ken, gave him advice he has passed down to his Kensei: "Don't think about it. Feel it." Ken took the message as he could do whatever he feels. Before he left, he made a vow to return and be stronger. His father runs and creates items for the SCRTC Meisters, the Special Items Development. When Ken came back to Japan, Jan didn't know who he was and clashes with him over the last Menchi Katsu, a ground meat mince and cutlet. Jan snags it and Ken chases him with a truck and takes it back. Master ShaFu reveals to the Gekiranger, to their surprise, that Ken is their newest member. Because of his forgetful nature, the four did not consider him an equal team mate and reduced his chances to be part of the team, which sadden his sister Sachiko. Master ShaFu offered Ken if he could put at least one member in his favor, he could stay on the team. After saving his sister from a falling object, Jan approved of Ken. After showing off his skills and killing Niwa, the RinJyu Crocodile-Fist user, the others felt it was best to try out having him as an ally.

He frequently uses the word 'Osu,' which is a karate term signifying 'patience with myself and others.' Ken was entrusted with the Soujyuto, the Virtuous Beast Sword but sold it. Retsu and Ken track down the SouJyuto to a woman, who was spurned by Bat Li long ago. Unfortunately he lost the SouJyuto once again, this time to Mele, when she held Sachiko hostage. Taking Bruce E.'s advice to heart battling Rageku, who burned down the Beast Origin Village, Ken tapped into Bruce E.'s GekiSoul. The SouJyuto then willing went into Ken's possession. SaiDain rose and Ken used it to release the Beast Power Bloom and destroy Kata with SaiDaiOh. In Episode 43, Ken revealed to a boy who had lost his mother a year eariler that his mother died of an unspecified illiness when he was young. He went into martial arts to keep his mind off bad memories. He sometimes clashes with Gou, in how he treats Jan when he refuses to fight Rio because Ken believed Gou was jealous. Ken was also insulted when Gou went on his own, to learn a new technique, but Ken didn't know that. It could be considered that Ken is fixated on the gender binary construct, for he always stresses what a 'real man' should be, pushing his ideal on other males that might not fit this society-devised mold. When it was threatened Ran would be forced to leave the team, Ken feared being in a male-only team and considered it 'dirty.' He loves women and enjoys their company very much, on New Years Eve he prayed for all women to be happy, including him being in their company. During the final battle, Ken, Gou, and the Kensei keep Ron at bay until Jan, Ran, and Retsu return. Ken witnessed the three Gekirangers seal Ron. After the battle was over, Ken returns to work at SCRTC Meisters. Jan bids farewell to Ken before he set off on his own journey.