Alternative names:
In Search of the Lost Future: Special; Ushinawareta Mirai wo Motomete: Ushinawareta Natsuyasumi wo Motomete; Ushinawareta Mirai wo Motomete Special; Ushinawareta Mirai wo Motomete Episode 13; In Search of the Lost Future Special; 失われた未来を求めて 第十三話「失われた夏休みを求めて」
Thirteenth episode delivered as a bonus Blu-ray disc to customers who pre-order all six Blu-ray volumes.