Hero was a high schooler living an ordinary life. One day, he meets a very strong and intelligent mechanical arm named "Mecha-ude." After a strange turn of events, the "Mecha-ude" started living inside Hero's hoodie, and the two's life full of trouble begins. As the boy and his "Mecha-ude" fight together and strengthen their bond, the two also meet new friends who fight alongside their own unique "Mecha-ude" partners. Among them, one of the heroines has two "Mecha-ude" that appear from her skirt. An active girl with characteristics totally opposite from Hero himself, he gradually becomes attracted to her. But the two are confronted with other "Mecha-ude" users who relentlessly search for the secret of "Mecha-ude."