Nagasarete Airantou

Wrapped in Mystery, Detective (Part One) (1x19)

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Ikuto and Suzu are invited to a hotspring resort. They are greeted by Sakuya, a mechanical doll built 130 years ago. Soon the others arrive and begin to start a competition for bathing with Ikuto. Suddenly, the masked fiend Beniyasha appears. Who is this masked man?