Riho Sayashi Writes the Ending to Her Own Story with “幸福失格”
What happens when the actress starring in a love story also writes the song that plays when the story starts to hurt? Riho Sayashi is giving audiences an unusually personal answer with “幸福失格 (Koufuku Shikkaku),” the ending theme for the upcoming live-action drama 付き合ってあげてもいいかな (How Do We Relationship?), in which she also takes the lead role. The Japanese pop single arrives August 31, putting Sayashi’s own words and voice alongside a story about love, loneliness, and the fear of finding happiness after becoming comfortable without it.
Sayashi’s career has already moved through several distinctly different stages. She began dancing as a child at Actors School Hiroshima before debuting in 2011 as a ninth-generation member of Morning Musume at just 12 years old. After leaving the group in 2015, she moved to the United States to study dance, eventually returning to entertainment and building a solo career on her own terms. She later founded her independent label Savo-r in 2021 before making her major-label debut with avex in 2025. That history makes OWN another interesting step in a career that has never stayed in one place for very long. Sayashi has spent years moving between dancing, idol performance, songwriting, and solo music, and now she is adding a major acting role to the mix while allowing her music to become part of that story. “幸福失格” sits right in the middle of all of those worlds.
“幸福失格” carries a darker emotional weight than the title might initially suggest. The song centers on someone who has convinced herself that happiness is not really meant for her, settling into a life where loneliness has become familiar enough to feel safe. Then love comes along and disrupts that balance. Instead of presenting falling in love as something simple or automatically comforting, Sayashi’s lyrics sit with the uncomfortable side of it: wanting someone deeply while knowing that allowing them close also means giving them the ability to hurt you.
That tension is what makes the song such an interesting match for How Do We Relationship?. The drama is adapted from Tamifull’s manga, a story that has already built a significant readership and online audience, and Sayashi is stepping into the role of someone whose own romantic experiences give the ending theme plenty of emotional context. Hearing her sing about someone who is afraid of happiness while watching her portray a character navigating relationships creates a connection between the music and drama that goes beyond simply placing a new single over the credits.
The second teaser for the series leans into that darker side of the story. Coming after the first teaser that quickly drew attention online, the new footage gives more room to the complicated emotions surrounding the characters and their relationships, with “幸福失格” providing the soundtrack. The song does not feel like an afterthought attached to the drama; its lyrics already carry the same questions the story is asking about how much a person is willing to risk when love becomes real.
There is also something particularly fitting about Sayashi being the person behind the song. She is not approaching the project solely as an actor brought in to perform someone else’s material. She wrote the lyrics herself, allowing her perspective as a musician to meet the character she is portraying on screen. That does not necessarily mean the song is a direct reflection of the character or Sayashi's own life, but the overlap makes the ending theme more intriguing because the audience gets to hear her interpretation of the emotional world she is helping bring to life.
“幸福失格” will also appear on Sayashi’s upcoming EP OWN, scheduled for September 2. The project follows lead single “I AM,” which arrived August 19, and continues a solo music career that has allowed Sayashi to explore a side of herself that is different from the idol career that first introduced her to audiences. With “幸福失格,” that musical work now intersects directly with her acting, creating a release that feels connected to something larger than the song itself.
付き合ってあげてもいいかな (How Do We Relationship?) premieres September 10 on MBS and will run for eight 24-minute episodes, with broadcasts continuing across regional networks through September. International viewers will be able to follow the series through GagaOOLala outside Japan and South Korea, with additional availability through Heavenly in South Korea and other regional platforms. Before the drama even reaches its first episode, “幸福失格” gives viewers an idea of the emotional territory waiting on the other side. It is a song about wanting happiness while being afraid of what happiness might cost, and coming to terms with the fact that love can be both the thing that saves you and the thing that scares you most. For Sayashi, there is an added layer to the release that makes it even more compelling: she is not only helping tell this story on screen, but she has written the song waiting for audiences when the story reaches its most vulnerable moments.
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