This volume of 「じつは義妹でした。〜最近できた義理の弟の距離感がやたら近いわけ〜」 centers on a household trying to hold itself together through two very different kinds of pressure: a farewell baseball game and a school trip that spirals into something much bigger. At the heart of it is a brother unsure of his path forward, and the lead's decision to give him a proper send-off from the sport he's leaving behind.

That retirement game becomes the volume's emotional pivot. As the match heats up, long-simmering feelings inside the family surface, not through dramatic confrontation but through the kind of pointed honesty that only comes out when everyone is already worn down. It is a story that trusts small, specific moments, a look across the room, an offhand comment during a huddle, to carry as much weight as any big reveal.

From there the setting shifts to Kyoto, where the long-awaited school trip finally arrives. But rest is in short supply: a key event in one character's early work life lands at the same time and place, turning the trip into a juggling act of schedules, obligations, and distractions. Amid all that, something happens that shakes the family's sense of itself to its foundation, raising questions about what holding a family together actually requires when circumstances refuse to cooperate.

Readers drawn to slice-of-life stories about blended households, where affection and awkwardness sit side by side, will find plenty to like here. The series doesn't rely on big twists so much as patient observation, following how people recalibrate their distance from one another after an unexpected jolt. For those who have followed the stepsiblings through earlier volumes, this one offers another step in their slow, uneven process of becoming a real family, tested by sport, travel, and the ordinary chaos of growing up.