Akarui mirai (2003) by Kiyoshi Kurosawa
aka: Bright future, Jellyfish

Mamoru (Tadanobu Asanu), sentenced to death after killing the entire family of his boss, gives away his pet jellyfish into the caring hands of his best friend and working colleague Yûji (Jô Odagiri). The cute baby creature, especially raised and trained to live in sweet water, soon finds its poisoning freedom and fertile happiness in the canals in and around Tokyo, while Yûji himself starts a new life with the help and love of Mamoru’s father.

seen at: pickledfeet private videothek