Osanai Kei enjoys a peaceful and happy life with his wife Osanai Kozue and daughter Osanai Ruri, but his wife and daughter die in an accident. Osanai Kei's life suddenly changes. One day, a man named Misumi Akihiko visits Osanai Kei. Misumi Akihiko tells him that on the day Osanai Kozue and Osanai Ruri died, Osanai Ruri, who was a complete stranger to him, was coming to see him. Misumi Akihiko tells him about a woman named Masaki Ruri, who he once loved. These people, who don't seem related, connect under the name of love.
One day Osomatsu meets an elderly gentleman who tells him a story about his son, who he lost in an accident. Coincidentally, Osomatsu looks similar to the deceased son, and so the gentleman wishes to adopt him. The man turns out to be the CEO of a big company, and, after overhearing the conversation, the rest of the sextuplets deicide to get into a fight with Osomatsu to decide who will become the heir. Later on, the story takes a sudden, unexpected twist as three strange men dressed in black show up.
The Matsuno brothers return to the big screen, this time in live-action and portrayed by the members of the Japanese boy band Snow Man! Osomatsu ends up meeting the CEO of a multi-trillion yen company, who wants to adopt Osomatsu as his own! The other brothers find out, and of course, they can't let that slide without a fight...
