According to HMV, the DVD & Blu-ray volume 7 of Ookiku Furikabutte ~Natsu no Taikai Hen~ will include an unaired episode 12.5. Director Mizushima posted in his blog that the special was made because they couldn't put the original manga episodes happened between the episode 12 and 13 within the TV series.

All-new animation offered throughout UNIQLO clothing stores in Japan on January 1, 2011. The DVD contains an exclusive version of Mayonaka Orchestra, by the Japanese rock band Aqua Timez. A limited number of the DVDs was offered as presents to people who bought UNIQLO's Naruto graphic T-shirts online or in their stores.

Nanami Simpson is a young girl. Her mother dies when she is young, and she goes to live with her father, Scott Simpson, on board a marine research vessel, the Peperonchino. Her father is a marine biologist, and he is in search of a creature known as the glowing whale. When he finds the bones of one of these, he is saddened, and resolves to change his mission toward preserving and caring for the creatures. Nanami befriends an Orca which she names Tico, and she goes swimming with it every day. Eventually, she learns to breathe underwater which astounds her father. Nanami nearly drowns one day, and one of the glowing whales saves her from certain death and returns her to the vessel, where her father finally gets to see it. (Source: ANN)

Minami-ke OVA bundled with the 10th volume of the manga.