Personality & Character
He is often maddened by his lack of ability to act to protect those around him, as well as his own PTSD symptoms. He started experiencing the symptoms after shooting his comrade John Humeray out of mercy when he couldn't free himself from the burning tank during the First Earth-Mars War at Tanegashima. He blames himself for what happened and is tortured by the memory until he was able to overcome it.
He fought at the Battle of Tanegashima against the Deucalion but the tanks were no match for Kataphrakts. He killed his comrade and friend Humeray because Humeray begged him to shoot him after his leg got caught in their tank and the tank ignited, burning Humeray alive and causing him excruciating pain. Koichiro, presumably the lone survivor of the one sided battle, wrote a report on how his team was annihilated. However, because of how unbelievable his story sounded, his higher-up saw him as a madman and thus dismissed his story; since then, people around Koichiro had very low respect for him as they were unable to believe how strong Koichiro claims the Martians are. In reality, it was later revealed that this was a ploy for hiding the seized Deucalion. (AZ: "Darkness Visible")
He became a drill instructor at Shin-awara High School. He dislikes how the school attempts to brainwash him and his colleagues to into thinking that they stand a chance against the Martians. (AZ: "Point of No Return")
After the Martians declared war on Earth, Marito is forced to return to active-duty. He piloted a KG-7 Areion. He now suffered major PTSD from his memories of the Battle of Tanegashima. (AZ: "Beyond the Horizon")
19 months after the assault of UFE HQ, he became part of the Clydesdale Platoon with Yuki Kaizuka, not wanting to return to the Deucalion battleship as it brought up bad memories. He believed he was rid of the memories but they returned during his battle with Count Mazuurek's Kataphrakts which could manipulate gravity just as the Deucalion he faced and aggressively fired with all his might whilst Count Mazuurek said it was futile but the battle was won after assistance from Ensign Kaizuka. After the battle Dr. Yagarai said he may have subconsciously used his fears of the Deucalion to strengthen himself. (AZ: "Soldiers' Pay")
They are both instructors working in the same school. Even though Yuki is his Kouhai, she seems to be more mature as she berates him for going to school drunk and looking unhygienic. Still, like how he treats his other comrades, he cares for her well-being and did everything he could to help her evacuate Shinawara. (AZ: "Beyond the Horizon", "The Children's Echelon")