"Mukodono" wasn't really that novel in terms of its plot where a man marries into his wife's family but the twist of making this man a superstar with a totally different character from his screen persona was probably what made the drama and interesting popular in the end. To a certain extent, Sakuraba Yuichiro is somewhat similar to Nagase where there is a gap between their cool screen persona and how they behave off-camera. As such, it seemed like this role was specially tailored for Nagase and he was rather at ease with this character. His interaction with Takeuchi Yuko was so good that it made the sequel two years later with Sakai Noriko pale in comparison. Of course, the sequel was also weak in other ways so it's not entirely to do with who his female lead was. With a strong and eye-catching supporting cast made up of Arashi's Aiba Masaki, Shinohara Ryoko, Suzuki Anju, Nomura Hironobu, Tsunku, Danta Yasunori, Akiyoshi Kumiko, Usui Ken and the very young Kamiki Ryunosuke, the drama did relatively well with an average of 15.3% which would be an achievement by today's standards.
As Sakuraba Yuichiro was an orphan in the story and aspired to have a family, the song "Hitoribocchi no Haburashi" (A toothbrush on its own) resonates with his loneliness after he misses the chance to tell someone he loves about his feelings. It uses the analogy of a single toothbrush in the bathroom to illustrate his loneliness and depicts his wish to see two toothbrushes side by side again in time to come.
If you are interested to hear this song, please view the PV here.