I'll tell you why so serious

Entertaining from beginning to end, it maintains the spirit of the franchise while establishing it's own seal with a fun cast

It's entirely possible that sending the audience out feeling lousy was intentional

It’s sentimental, ridiculously long and only occasionally funny

A musical biopic of the blind shamisen (a Japanese string instrument) player Chikuzan Takahashi. Narratively, it's pretty standard - one might call it the Japanese Ray and not be too far off. But it's well acted and well shot, with a lot of interesting settings and period detail (the setting is early 20th Century rural Japan, up to WWII). Ryuzo Hayashi stars as Chikuzan. Kaneto Shindo's wife and frequent star Nobuko Otowa co-stars as Chikuzan's mother. Well worth checking out if you can find it. This was nominated for the Japanese Academy award for Best Picture in the first year of its existence, but lost to Yoji Yamada's The Yellow Handkerchief.