Sora and Umi (both played by Lee Tae-kyung) who were born to a Japanese father and a Korean mother and raised in South Korea. Sora now lives in Shanghai and works as an illustrator. When she meets a Japanese guy named Mochizuki, they become close. This is when her sibling Umi visits. Umi was born inter-sex and had undergone gender reassignment surgery to become a woman. Umi encourages Sora and Mochizuki to fall in love, but Sora becomes mentally unstable.
| Actor | Role |
|---|---|
 Lee Tae-kyungSora Asami / Umi Asami | Sora Asami / Umi Asami |
 Tsuyoshi AbeHayato Mochizuki | Hayato Mochizuki |
| AAgnes ChanXin Lan | Xin Lan |
| TTomoko HayakawaHayato's Mother | Hayato's Mother |
| LLina HeNot listed | Not listed |
| MMyung-Hwa HongJisook Kim | Jisook Kim |
| XXiaoming JinBingxuan Gao | Bingxuan Gao |
| EEun-ji JoNot listed | Not listed |
| GGaseul KimNot listed | Not listed |
| MMin-Seong KimNot listed | Not listed |
| JJua LeeNot listed | Not listed |
| FFan LiNot listed | Not listed |
| TTaisetsu MikiNot listed | Not listed |
| KKenichi MorimotoNot listed | Not listed |
| WWoohyeong SonNot listed | Not listed |
 Hiromitsu TakedaTakashi Asami | Takashi Asami |
| JJenyao TsaiJiayi Wu | Jiayi Wu |
| WWang MeiziShufen Wei | Shufen Wei |
| CCongxi YangNot listed | Not listed |
| YYalin ZhouWenxuan Xu | Wenxuan Xu |