Manabu Midoro is the son of Dr. Midoro, a Nobel Prize-winning biologist who is among the first humans to believe the warnings brought by the microids Yanma, Ageha, and Mamezo. Despite being the child of a celebrated scientist, Manabu is portrayed as an underachieving student who has repeated a year in middle school. He was a member of his school’s kendo club until his expulsion, and he continues to wield a bamboo sword (shinai) as his primary weapon in battle. His personality is marked by a quick tendency to blush when encountering attractive girls, revealing a shy and impressionable side.

Manabu’s central motivation is supporting his father and the microids in their struggle to protect humanity from the insect empire Gidoron. He joins Dr. Midoro in offering refuge and assistance to the three tiny heroes, acting as a youthful ally who can operate in settings where an adult’s presence might draw suspicion. His role in the story is that of a human bridge between ordinary society and the extraordinary conflict unfolding at a miniature scale. He is often the one who carries out hands-on tasks, using his kendo skills to defend against cybernetic insect threats.

His primary relationship is with his father, Dr. Midoro, with whom he shares a bond of trust and shared purpose. He also develops a cooperative friendship with the microids, especially Yanma, and proves himself a loyal companion in their dangerous missions. Over the course of the series, Manabu grows from a somewhat wayward student into a braver and more responsible figure, though his impulsive and occasionally comedic reactions to romance remain a consistent trait. His notable abilities include his kendo training, which provides him with a practical combat skill against the insectoid enemies, and his willingness to act despite his ordinary human limitations. This combination of youthful vulnerability, loyalty, and a touch of martial discipline defines him as a relatable human presence amidst the fantastic elements of the story.