The Reason for Fukigen is?

Mikako pauses her clothing synthesis one night out of anxiety about the proximity of the upcoming flea market along with the love triangle Yuusuke is involved in with both Mariko and Ayumi before frenzily resuming her efforts. During the school commute the next morning, Tsutomu explains that Ayumi has offered her shed for Akindo to store its merchandise -- if the members are willing to forego the afternoon classes that day. An afternoon detention sets the stage for Yuusuke to inadvertently slight Mariko when he gives Ayumi a ride home to compensate for Mariko frigidly repulsing her during which he entreats Ayumi to see the big picture of Mariko Nakasu before riding off. Yuusuke exhibiting his compensatory volition for her company does very little to dissuade Mariko from amplifying her vendetta with Ayumi -- the incendiary adversarial divergent concourse thereof ending with the latter's counsel to behave toward Yuusuke as a human being rather than as merely a chauffeur; while Mariko fumes at Ayumi's admonition being very similar to Shintaro's earlier reproof, Mikako proudly shows off to Tsutomu her latest handiwork that she plans to sell at the flea market oblivious to Ruriko seriously considering a decisive exhibition of family government that could extinguish her vendor volition. Tsutomu taking in stride the abrupt arrival of a rainstorm along with Ruriko's maternal interloping ultimately unsettles Mikako into sharing her prologue of having no affinity for group activities before Akindo which she fears will have stormy sailing ahead.