I wanted to write something mainly because I believe the ~~incest~~ tag is not needed and might make the potential readers hesitant :') So here's my two cents:

This is the story of Sena, a reserved writer whose entire world revolves around her older sister, Yuuna. With no other family or close friends, Sena begins to grow emotionally through the influence of new relationships—particularly with Kiku, a woman who becomes a key figure in both sisters' lives.

kinda SPOILERS AHEAD!

Before delving into how Kiku changes things, I want to talk more about the relationship between the sisters:

I noticed the ~~incest~~ tag only after reading five or six chapters. Early on, Sena's way of speaking about her sister does feel a little romantic (very vague, but still), and it made me pause. I wasn't sure if I wanted to keep reading but I wantd the see where the characters were taking me. What unfolds is an exploration of love—not just romantic, but familial, platonic, and everything in between.

Through Sena and Yuuna, we witness two people trying to understand what it means to care for someone deeply. As Sena herself says in the final chapter, the love she felt for Yuuna was not the same as the love she later develops for Kiku. I don’t believe there were ever true romantic feelings between the sisters. Instead, Sena’s emotions were vague and confused—understandably so, given their circumstances.

Their parents are completely absent in the story. Yuuna even mentions at one point that their parents never really cared about them. That absence left them with only each other, forcing Yuuna to play both protector and provider. She tried to be everything for Sena—mother, father, sister—and that responsibility gradually built emotional walls between them.

Both characters, in my opinion, were lost. They didn’t know how to express or even name their feelings, because they never had the chance to grow emotionally. Sena’s "love" for her sister was really just fear—fear of losing the one person she had, fear of being alone. Her dependence on Yuuna made her unable to function without her.

Then comes Kiku, introduced as Yuuna’s girlfriend. While their romantic relationship doesn't involve any romantic feelings, Yuuna loves her presence and considers her part of their little family. With Kiku, Yuuna doesn’t need to pretend or carry any emotional weight. She can finally be herself, which is a turning point in her growth.

Obviously their romantic relationship doesn’t last long but Yuuna and Kiku remain close. Eventually, Kiku realizes she has genuine romantic feelings for Sena. At first, Sena can't imagine loving anyone but Yuuna. But when Yuuna leaves for work abroad, Kiku steps in—not to replace her, but to support Sena in a different way. Slowly, their bond evolves into something deeper and more mature, something Sena didn’t even know was possible.

My only very minor complaint would be Kiku. She was a saint, was almost too perfect—more of a guide than a fully fleshed-out character. I wanted to see more of her. I wanted to see more in general, this felt too short!

Still, I enjoyed watching the emotional journey of the sisters, especially Sena’s transformation. The manga explores different forms of love with care, showing how relationships shape us and help us grow.

I’d definitely recommend it. It’s a nice read. And in my opinion, the ~~incest~~ tag doesn’t do it justice!!!! It oversimplifies something far more complex and human.