Mitsuki’s co-worker at the Japanese space agency. A smart, good-humored, heavy-set guy, Kaito has a competitive relationship with Mitsuki, but understands she is smarter than him.
Launch of the Hoshi-12
Kaito works alongside Mitsuki on the day of the Hoshi-12 launch — a one-year trip to the International Space Station. Aboard the shuttle is Hinata Murai, along with two other astronauts, though Kaito seems fixated on Hinata and exactly how she ended up with her boyfriend, who by his account, is a terrible actor.
Three hours after having lost communication with the shuttle, they call in Mitsuki, who discovers that the shuttle has ruptured, presumably killing all the astronauts on board.
Investigation of the Hoshi-12
When Mitsuki returns to work, Kaito informs her that the government has issued an independent commission to determine just how the shuttle ruptured. In fear that they would miss something, Mitsuki steals Hashimoto's badge and breaks into the comms room along with Kaito. And the two of them watch the final moments of the shuttle before it ruptured, discovering that something hit the Hoshi-12
When Kaito and Mitsuki are taken in for questioning by Hashimoto, Kaito does not support Mitsuki's claim that something may have hit the shuttle, causing it to rupture. This results in Mitsuki being fired.
Kaito helps Mitsuki and Ikuro infiltrate the satellite station as authorized JASA officials in order to possibly make contact with the aliens while using the audio from the last moments of the shuttle. They eventually discover a distress beacon from the shuttle, but the police arrive to take Mitsuki, Kaito, and Ikuro away before they can pinpoint the location of it.
Fortunately, Mitsuki is able to bargain their freedom as well as her position as comms team leader. While attempting to make contact with the aliens, Kaito asks why she didn't tell him about her relationship with Hinata and then reveals that he cares about Mitsuki more than anyone else.