Overview was kind of abysmal so I ran it through ChatGPT, this makes way more sense:
Story
The protagonist, Kazumi Tsukayama, had a beloved wife named Nodoka Tsukayama. During his university days, Kazumi, motivated by casual relationships, was a member of a circle dedicated to such pursuits, engaging with various women. However, after meeting Nodoka, he abandoned both the circle and his playboy lifestyle, dedicating himself to loving only her.
Several years into their happy marriage, a news article reveals that the circle Kazumi once belonged to had caused trouble in sexual relationships with several women. Although Kazumi had already distanced himself from the circle, he feared what his wife would think if she discovered his past.
One day, during these anxious times, Toshio, an acquaintance from Kazumi's university days, appears. Toshio informs Kazumi that he knows about his involvement in that circle and hands him a USB flash drive. The files on the drive depict images of Nodoka and Toshio in an intimate embrace from their past. When questioned, Toshio admits to having dated Nodoka before. Kazumi becomes wary, believing that Toshio has come for revenge, resentful for taking Nodoka away.
As these events unfold, something begins to gradually change in Kazumi's surroundings.