Special included on Kuroko no Basket Fan Disc 1: Owara nai Natsu.

Invited for a anniversary celebration, Kindaichi, Miyuki and inspector Kenmochi re-visit the Opera House. There they discover that a play of "The Phantom of the Opera" is being rehearsed again. However, it doesn't take long when members of the acting troupe are killed by the "Phantom". Kindaichi will once again have to solve a murder series in the Opera House. (Source: ANN)

It is a cross over between the series Lupin III and Detective Conan and takes place after the television special Lupin the 3rd vs Detective Conan. The plot follows Conan Edogawa who sets out to apprehend Arsène Lupin III, the suspect of stealing a jewel called Cherry Sapphire.

(Souce: Wikipedia)

A dying mob boss entrusts Lupin with a diamond that supposedly is the key to a vast treasure. But when Lupin is attacked by an assassin and saves a mysterious girl from trouble, it becomes clear that that there's more to this treasure then meets the eye... 

(Source: ANN)