On the banks of the Sumida River in Asakusa, Tokyo, ancient buildings live in the unremarkable Okawabata Detective Agency. The detective agency consists of three people. They only know how to make models. The good-tempered director Okawabata Ippei (Ishibashi Renji), the big-chested and brainless receptionist Xiaohui (Koizumi Maya), and the investigator Muraki (Odagiri Joe) who sleeps on the sofa when he is not commissioned. Muraki often has some predictable nightmares, and the clients who come to the door are more or less related to his dreams. In the current economic downturn, Okawabata Detective Agency has a wide range of businesses, and sometimes even plays a role similar to a convenience house. Their clients come from all walks of life, including gang leaders, comedians, bakery uncles, otakus, etc. What they are looking for ranges from delicious wonton noodles after the war to the mysterious snow woman from twenty years ago, which is enough to make people scratch their scalp. In the process, Muraki and his friends also get to know the touching or sighing side of others... This film is based on the manga by Hijikata Yumine (original work) and Tanaka Asashio (illustration).