My Sister is My Girlfriend!? Sexual Relationship for Two Nights and Three Days 4

Editorial Review

★3.8 / 5 — henhenta editorial rating (our own assessment, not the DLsite official user score)

Fake-relationship romance meets taboo family dynamics in this fourth installment of a series built on a durable premise: a sibling cover story that gradually stops feeling like a cover story. Within the incest-themed corner of adult manga, the “pretend couple” setup is a popular device because it supplies a ready-made excuse for escalating intimacy, and this entry leans on it fully.

What distinguishes the volume is its situational structure. The group trip gives the pair a semi-public stage where the narrator must keep up appearances, so the physical closeness Nonoka engineers (the incidental contact, the shared bed “like a couple would”) carries real friction between performance and desire. The synopsis frames the dynamic as a power imbalance of personality rather than circumstance: Nonoka is “always strong,” and the protagonist’s protests of “we’re just acting” are consistently undercut by his own body. That teasing-heroine, flustered-protagonist rhythm is a staple of the genre, but the trip setting gives it more narrative momentum than a single-room encounter would. The promise of a first-time threshold being crossed also gives this chapter a clear escalation point, which suits its place in an ongoing series.

As a 単話 (single-story) release with an English edition, it is a quick, self-contained read. It will not demand heavy investment in backstory, though readers who have followed the earlier volumes will probably appreciate the payoff more. The tags are sparse, so expect a focused, premise-driven piece rather than anything formally experimental.

It is best suited to readers who enjoy domineering, playful heroines, “acting turns real” tension, and taboo-flavored romantic comedy with a heavy erotic emphasis.

Verdict: a competent, premise-forward entry that delivers exactly the teasing, boundary-slipping dynamic its title promises.