Mokusuke Isshū is the third son of the Isshū family in the anime Tentō Mushi no Uta. He is eight years old and in the third grade, and he has a noticeably stout build. Despite his appearance, he possesses a warm and loving nature toward his siblings. His personality combines a gentle, thoughtful disposition with a practical, inventive streak: he enjoys creating gadgets and devising clever solutions to the everyday problems the family faces, often bringing humor to difficult situations. At the same time, he has a spiritual side, as he performs Buddhist prayers and has expressed a desire to become a priest when he grows up. In the story, Mokusuke serves as a supportive, resourceful member of the seven siblings, using his creativity to ease their struggles and maintain morale. He shares close bonds with each of his brothers and sisters, particularly with his older brother Kaji and his younger siblings, and his inventions often help the family in their efforts to live independently after the loss of their parents. Over the course of the series, Mokusuke matures while retaining both his inventive spirit and his deep sense of familial devotion. His notable abilities include mechanical ingenuity and the performance of Buddhist rites, reflecting a blend of worldly cleverness and personal faith.