Touma pays the Minami sisters a visit with an unknown payload whose revelation Chiaki objects in Haruka's absence. Though she inhibits herself for the time being, Kana begins to succumb to avarice when Fujioka comes for a visit. What follows is an exercise in game theory in which Kana leads Chiaki through an enigmatic scenario to obfuscate her volition for having the entire payload to herself since Haruka's estimated arrival time is an unknown variable. Kana's only mistake is that she forgets to consider all the players. The next arc features Haruka and Chiaki being rather vague and indirect about the supermarket and the route thereof as well as a neighborhood dog giving way to Chiaki encountering a shopping list that she suspects that Kana tampered with. The arc thereafter details Hayami comparing notes with Maki regarding Hosaka before she gets the idea to wield Hosaka's computations as her plaything. Hosaka tries befriending Maki and Atsuko but is puzzled when they swiftly flee. The final arc features Haruka taking notes from a cooking show about the preparation of curry while detecting the necessity of visiting the supermarket. Chiaki taking on this stewardship with the very notes that Haruka was taking earlier ends up inspiring Hosaka and herself an extra spicy curry.

A euphoric beach outing having the dysphoric prologue of Kana being carsick is reflected upon warmly by Uchida and Yoshino who have taken the whole experience in stride. Yoshino remarks that Chiaki has become attached to Fujioka as an elder sibling in much the same way that Kana has with Uchida and her. Chiaki's exhortation for the whereabouts of her teddy bear disrupts the reminiscence; fortunately, Fujioka brings it back and Kana successfully obfuscates her role. Maki tempers her disdain for her summer homework by successfully wielding Fujioka's computations as her plaything until Kana and Chiaki extinguish her machinations. The next arc features Uchida having a near-complete computation crash as she struggles to complete her summer homework without Chiaki's counsel as the penance for abusing Chiaki's goodwill. Fortunately, Chiaki is not heartless; she eventually relents after seeing Uchida and Makoto's demonstration of interdependence being a two-way street. The final arc features Kana's attempts to forestall the approaching autumn backfiring upon her as Chiaki, galvanized by all the pranks Kana played on her, retaliates by eating Kana's dinner in addition to her own.

During a lazy afternoon, Kana decides to help herself to some oranges while Touma and Chiaki read at the kotatsu before getting the idea to snack on an orange. It is not long before Makoto and Uchida learn the root cause: Kana delivering a preemptory »Hands off my oranges; go get your own!!!« karate chop to both Chiaki and Touma. Another arc has everybody galvanized by the Yuletime ambiance: Chiaki synthesizing a huge stocking and leaving it to chance what present she receives, Touma learning to appreciate »useless/annoying« family rituals, and Hosaka acquiring a part-time job as a cake salesman dressed in a Santa Claus suit even though he does not encounter Haruka by that avenue as per his daydream. Haruka hosts a Yuletime banquet at her house.

Fujioka approaching Kana with a book for Chiaki and Riko computing the approach thereof gives way to another girl named Hiroko taking notes of the whole scenario from afar before conscripting Riko into an exercise to build up the courage necessary for a confession that flounders. The next arc details Kana conducting her volition of a study session at her home with Keiko and Fujioka that Riko decides to capitalize upon. The study session's academic success contrasts with the fact that Riko has not once confessed her feelings seeming content to enjoy the ambiance of proximity to Fujioka. Fujioka, Riko, and Keiko nearly have a computation crash when they go into the bathroom to find the bathtub covered in order to keep the water hot and decide to shower instead. The arc the follows thereafter details the epilogue of a recent test in which Riko, Fujioka, and Kana's test scores are close to Keiko's perfect score. The final arc begins with a conversation between Makoto and Touma over being given chocolates as a Valentine's Day joke prompting Kana deciding to play Othello after telling Chiaki that she needs to practice celebrating Valentine's Day to gain the experience.