——I want to be a man who can walk beside her with my head held high.

The protagonist, Kōsuke Takahara, is in love with his childhood friend, Suzume Azumino, who is one year his senior.

Having a long-standing family relationship, his relationship with Suzume had also continued for a long time like "siblings." However, he had decided to put an end to that relationship this summer by confessing his feelings during a family trip with both families.

On the first day of the trip, an unexpected problem arose for Kōsuke and his family. Due to a booking error, they were short one room.

Kōsuke, thinking there was nothing to be done, offered his room to Suzume and proceeded to make arrangements to share a room with his parents. However, Suzume spoke up to him.

"Wouldn't it be okay if Kō-kun and I shared a room?"

At that suggestion, Kōsuke was flustered, thinking that even if they were childhood friends, it was inappropriate for a young man and woman to share a room... But in the end, Suzume prevailed, and they ended up sharing a room.

"...I guess Suzume doesn't see me as a man after all..."

Kōsuke, seeing that Suzume didn't seem to mind sharing a room, quickly became anxious about the future.

But he didn't know. That Suzume, who had suggested sharing a room, had also decided to confess her feelings to Kōsuke during this trip——.