Cold Sleep

There is a famous thief group, Cureflone. The members are White Flone and Black Flone and they fly around the town in search of a precious stone called Pure Stone every night. Shoutaro is a private detective and he tries to catch them using a robot he invented. Also, Dr. Chan takes part in a battle for the Pure Stone.... An exciting three way fight now breaks out!

[From vndbreview]