Yuu takes an interest in Koizumi, the quiet new transfer student. After joining her in a ramen shop, Yuu discovers Koizumi's love of ramen; Yuu tries Maayu ramen from the school cafeteria and learns about different styles of ramen; Yuu follows Koizumi to a restaurant and learns about ramen broths and sauces.
After her boyfriend breaks up with her, Misa follows Koizumi to a ramen shop where they both order the spicy Hokkyoku ramen; Jun finds herself visiting a ramen shop after learning about peculiar ramen flavors from Koizumi.
Yuu tries to invite Koizumi to a hamburger restaurant; Yuu joins Koizumi at a ramen restaurant where the seats are flavor concentration booths; After finding Koizumi collapsed from starvation, Yuu brings Koizumi to her house.
Yuu follows Koizumi after school believing she is meeting with a boy; Yuu and Misa visit a ramen restaurant after a day of shopping; after having a stressful day, Jun goes to a convenience store and ends up eating ramen there with Koizumi.
Yuu provides commentary as Koizumi enjoys a bowl of tomato ramen; Jun goes with Koizumi to try a green ramen that is rich in euglena; Yuu waits in line for a popular ramen shop in place of Koizumi after learning she dislikes long lines.
Yuu's older brother, Shuu, crosses paths with Koizumi one morning; after learning about hiyashi ramen from Koizumi, the girls are enticed to try it on a hot summer day; Koizumi encounters a lost little girl while she visits a museum.
Summer break has started and Yuu, Misa, and Jun go to an amusement park and visit the city of Asakusa. While in the city, Yuu comes across Koizumi on a "nationwide" ramen tour.
While Yuu and Misa go to the beach, Koizumi and Jun go to a shop that sells a variety of instant ramen from all across the country; Shuu and his friends go to a ramen shop that serves iekei-style ramen.
Koizumi goes on a mountain hike; Misa's younger brother, Kenta, becomes motivated to finish the massive Buta Yarou ramen when he sees Koizumi; Misa follows Koizumi to a ramen shop that sells ramen full of pork back fat.
Yuu witnesses Koizumi eat ramen that has a blue broth; Shuu takes Yuu to sushi bar where Koizumi also happens to be at; the four girls go to a Chinese restaurant.
Yuu tries to recall the name of a ramen she had when she was a little kid; Koizumi travels to Osaka to try the ramen there and is accompanied by a woman who decides to act as her bodyguard.
On her way back to Tokyo from Osaka, Yuu finds herself stranded in Nagoya believing she spotted Koizumi there; Koizumi catches a cold and Yuu begins to worry about her when she stops attending classes.