Back Number’s Mutual Love Songs: Popular Song Ranking [2026]

Happinessback number11rank/position

Happiness / back number (cover)

The protagonist is a girl who has an unrequited crush on a man, but he likes someone else…

Even so, it’s a masterpiece that conveys her straightforward feelings of “I only wish for your happiness.” Because she’s always by his side, she sees things she doesn’t want to see and it hurts, yet she wants to stay close because she loves him…

It’s a truly heartrending love song.

Winter and Springback number12rank/position

back number – Winter and Spring

Released by back number in January 2024, this piece portrays the feelings of a heartbroken woman by overlaying them with scenes of snowmelt.

The music video features a standout performance by actress Anna Ishii, and the visual beauty—directed by Iyori Shimizu—also drew attention.

With a melody that evokes both the end of love and a new beginning, this work resonates deeply and is recommended for those trying to overcome the pain of heartbreak or seeking to rediscover their own worth.

It’s a song you’ll want to listen to alone on a quiet winter night.

Until the day I can no longer rememberback number13rank/position

back number – Until the Day It Becomes Unrememberable (Short ver.)

For those who can’t stop thinking about an ex, the song you should listen to is “Omoidasenakunaru Sono Hi Made” (“Until the Day I Can No Longer Remember”).

It was released in 2011 by the rock band back number, known for their many love songs.

The track features a passionate band performance enriched with strings.

Many listeners will relate to the lyrics overflowing with feelings for a lover from whom they’ve grown apart.

It’s a unrequited-love song that portrays the ache in a heart that once shared both joy and sorrow as a pair.

Give this sentimental ballad about a wintertime parting a listen.

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cotton candyback number14rank/position

back number – Watagashi (full)

A heartwarming love song that gently embraces the bittersweet feelings of a summer festival.

It delicately portrays the fluttering excitement in your chest, the frustration of wanting to hold hands but not being able to take that step, and the emotions stirred by the other person’s casual gestures, all set to a calm melody.

Released in July 2012, it was chosen as the opening theme for TBS’s “COUNT DOWN TV,” capturing the hearts of many.

The song resonates with listeners’ own summer memories, making it perfect for karaoke, where you can fully immerse yourself in its world.

With a softly accompanying melody and few sudden pitch changes, it’s an easy, enjoyable choice for karaoke.

Happy Endingback number15rank/position

back number – Happy End (full)

This song was chosen as the theme for the film “My Tomorrow, Your Yesterday,” which portrays a heartrending love story.

Its poignant, heart‑tightening lyrics and beautiful melody leave a strong impression.

Released in November 2016 as back number’s 16th single, it was written and composed by Iyori Shimizu.

The music video features Tori Matsuzaka and Haruna Kawaguchi, and its delicate depiction of the pain of long-distance relationships and the struggle of parting drew significant attention.

If you’ve experienced a breakup or are troubled about a relationship with someone important, this is a song that will speak to your heart—please give it a listen.