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' fights together and strengthen their bonds, the two also meets new friends who also fights along with each of their own unique 'Mecha-ude' partners. Out of those, one of the heroine has two 'Mecha-ude' which appears out of her skirt. An active girl with a totally opposite characteristics from hero himself, he gradually becomes attracted to her. But the two are confronted with other 'Mecha-ude' users who are in search of the secret of 'Mecha-ude' relentlessly.