If an Unrelated Sister and Brother Are Both in Love With Each Other, Isn’t It Just a Matter of Time Before They Get Together?

The protagonist, Haruhito Ishimoto, a second-year high school student, lost his parents in an accident. Now, he lives alone with his 24-year-old sister, Kinoka, who works to support him. However, Haruhito harbors feelings for Kinoka. Upon discovering that they are not biologically related, he struggles with the moral dilemma of whether or not to confess his feelings, knowing it might be wrong.

On the other hand, Kinoka also finds herself seeing Haruhito as more than just a younger brother. Despite her internal conflict, she can no longer suppress her growing emotions for him…