A collaboration campaign between the TV anime “Ao no Hako” Season 2 and the karaoke chain Big Echo will be held from September 29 to November 16, 2026, at five locations in Tokyo, Kanagawa, Aichi, and Osaka, featuring an exhibition of stills from the anime. For a limited time of seven days starting October 4—the day the anime premieres—customers who make an advance online reservation and spend at least 1,000 yen (tax included) per person on karaoke will receive a non-commercial official poster.