Space Ironman Kyodain

(from ebookjapan):
A young boy, Kenji, witnesses a flying saucer, follows it and discovers it has landed! However, a mysterious robot appears from the saucer and attacks him. Just as he is on the verge of disaster, two robots save Kenji and ......? They call themselves "Kyodain" and tell him that they are substitute robots for Kenji's two brothers who went missing three years ago. ──── The book contains five gems of SF short stories, including "Space Iron Man Kyodain," a SF action story in which the brothers' robots go on a rampage, and "The Ominous Star of Nostradamus".