Okitegami Kyouko no Urabyoushi

The ninth instalment of the Boukyaku Tantei Series.

The forgetful detective, Okitegami Kyouko, is arrested as a suspect in a robbery-murder case. She was found asleep at the scene, clutching the bloody murder weapon, and had forgotten her memories of the incident. When Kyouko-san offers to investigate the case from inside her cage, she is confronted by Hitaisei, a strong police officer nicknamed "the False Accuser". As he struggles with his pride as a police officer, he chooses to ask for the help of the "forgetful detective expert", Kakushidate Yakusuke...?

(Source: Kodansha, translated)