After a successful heist, Kid receives a phone call from a payphone and is told to stop stealing gems. At school, Kaito promises Aoko he will attend her birthday party, which is on the same day as his heist for the gem known as the Blue Birthday.
After seemingly killed, the organization steal the Blue Birthday and departs. Kaito follows them and learns the organization are searching for an immortality granting jewel known as Pandora which resides in a large gemstone and can only be found if shone in the moonlight. After determining the Blue Birthday is not the gem they are looking for, Kaito threatens to find and destroy Pandora before they can find it. Unable to make it to Aoko's birthday in time, Kaito rigs an apartment complex's lights to spell out Happy Birthday Aoko. Elsewhere, the organization contacts their boss who decides to contact another of their organization's member known as Spider to counter Kid.
In the manga, the string of flags that Kaito pulls out of his shirt pocket are all flags of various countries. To make the animation easier, the special changes this to flags with simple shapes like clovers and diamonds.
The manga has only one scene that takes place during Aoko's birthday party proper. The special inserts a few more scenes of the party in-between the Blue Birthday heist, where Aoko's friends enjoy party games while Aoko herself wonders where Kaito is.
In the manga, Kid throws the real Blue Birthday back immediately after dodging the gunfire from Snake and his cronies. In the special, he returns fire with his card-gun and disarms them before throwing the sapphire back.
In the manga, Inspector Nakamori wonders if it's supposed to be "someone's birthday" when he finds the Blue Birthday. In the special, this line is moved to the Inspector's celebratory party.
The epilogue featuring the leader of the organization contacting Spider is unique to the special.