One cold day in winter, Miniwa Tsumiki joins her close friend and crush Otonashi Io to a visit on the Arcade along their friends Katase Mayoi, Haruno Hime and Inui Sakaki.

Part A: The group pays a visit to Sakaki's older sister Miiko's Cake Shop, the Hatch Potch, where Io and Sakaki work. Part B: Valentine's Day is on the corner and Tsumiki, Mayoi and Hime assemble to make chocolates for the group.

Part A: The winter is almost over. The gang divide themselves into two teams and play snowball but Mayoi and Sakaki have some tricks up their sleeves. Part B: Cooking class. In a different team than Io, Tsumiki takes the opportunity to show him her culinary skills.

Part A: Due to a teachers' meeting, afternoon club activities have been cancelled, so Mayoi announces a "Kick the Can" game, for which the students are divided into two teams: hiders and seekers with a special penality for the losing team. Part B: The school radio now turns into a school TV with special guests Io and Sakaki, who have to give advice to problems sent in by girl students.

Part A: After the five have discussed some embarrassing details of the physical check-up, they settle on a competitive volleyball match. The losing team has to fight for the most popular lunch items in the school cafeteria. Part B: The five go on a picnic where they decide to play Frisbee before the meal. Io sits apart from the others playing with the many cats that become friendly with him, much to their admiration.

Part A: It's time for summer uniforms and the students are assigned to clean the swimming pool. It does not take long for them to make a mess of it. Part B: The afternoon before the test, Mayoi suggests a study group meeting in Io's house. Sakaki cannot go because he has a shift in Hatch Potch, so it is Io and the three girls. After the test, the weather turns rainy and there are not enough umbrellas.

Although summer homework is still waiting for them to finish, except for Io, the five decide to take a train trip to a mountain resort. In the Drift race, they race to the mountain resort, and race along the mountain in a parody of Initial D.

Part A: The girls decide to pay a visit to Io's place as Tsumiki's air conditioner is broken. However, Mayoi and Sakaki are still held by the task of finishing up their homework, and urges the others to not worry about them and have some fun by themselves, despite their behavior says otherwise. Part B: The gang attends the summer festival together, facing several humorous situations as they try some of its attractions.

The time comes for the school festival and the five decide to mount a crêpe stand (named "Tsutsumin!" meaning something like "I wrapped") together, which turns out to be a great success. Io serves as the cook but also sews Tsumiki's mascot uniform by hand, and promises the first crêpe to her. Mayoi wears no lab coat over her waitress uniform.

Part A: Mayoi buys a bear costume for cheap and decides to put it to use by scaring as many people as she can. Part B: Mayoi is planning to have a party on Christmas Eve but has to put it off to Christmas Day as Hime and Io promised to work in Hatch Potch. She and Tsumiki also stand in to help Io sell Christmas cakes in front of the shop.

Part A: The five go to the New Year's festival. The following day, they come together at the Inuis' place where their teacher Kikue Sakuragawa, who seems to be Miiko's friend, is also present. They talk about new year's resolutions, play games, and have a meal. Part B: It's a very cold day. Due to a flu epidemic, more than half the class is absent, school finishes after lunch. Tsumiki and Io appear to have a 'moment' which leaves Io rather confused and flustered.

Part A: It's valentine's day and the girls decide to make some chocolates, at school Tsumiki forgot the chocolates she wanted to give to Io. Everybody was having fun trading chocolates except Tsumiki. After school, Tsumiki runs back to her house to get the chocolate, but on the way back the chocolates got wet and then Io arrives with his umbrella to protect Tsumiki from the rain. Even when the chocolates were all wet, Io still accepted the chocolates. Part B: It's White Day and the boys (inclusive Kyoya) decide to make chocolate marshmallow, white chocolate cookies and gem sweets as return for the chocolates at valentine's day. Sakaki has secretly made some pig feet marshmallows as revenge for Mayoi's frog-flesh chocolate (episode 2, but it backfires before the end). At the end Io and Tsumiki talked about the kittyface on Tsumiki's gem sweetbox that Io has specially made for her.