- Title: Sekai de Ichiban Kodoku na Lover (世界で一番孤独なLover, The worlds' number one lonely Lover?)
- Artist: Nogizaka46
- Single: Girl's Rule
- Lyrics: Akimoto Yasushi
- Composition: Kawahara Mineaki
- Arrangement: Hyakkoku Hajime
- Other Related Works: BADBOYS J (Insert Theme)
- 1st Generation: Akimoto Manatsu, Ikuta Erika, Ikoma Rina, Ito Marika, Inoue Sayuri, Saito Yuri, Sakurai Reika, Shiraishi Mai, Takayama Kazumi, Nakada Kana, Nishino Nanase, Hashimoto Nanami, Fukagawa Mai, Hoshino Minami, Matsumura Sayuri, Wakatsuki Yumi
- This song was used as the insert theme for the drama BADBOYS J featuring Nogizaka46's Hashimoto Nanami, Sakurai Reika, Takayama Kazumi, Wakatsuki Yumi, Noujo Ami, Matsumura Sayuri, Akimoto Manatsu, Ito Marika, Ito Nene, AKB48's Itano Tomomi, and several other cast from Johnny & Associates.
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