A timeline of events for The Summer You Were There. Be warned: all spoilers are unmarked.
- 2015-16:
- Shizuku helped Kaori get a book and told her that she looked cuter without glasses. Shizuku forgot about this encounter, but Kaori never did.
- What began as Shizuku's misguided attempts to help her classmate Ruri escalated into bullying, and Shizuku eventually pushed Ruri while the latter was carrying curry. In response, Seri slapped Shizuku and the rest of the school ostracized Shizuku. Kaori, who was in the school for a year, heard rumors. At
- 2016-17: The Hoshikawa family adopted their dog Shion from relatives.
- 2015-20: At some point during this period, Kaori befriended Ruri and Seri.
- July 2019: Shizuku started work on her first novel, "Girls Lovers Suicide." The reception was initially positive, but turned intensely negative after someone found out that the novel resembled a real suicide, driving Shizuku into despair.
- January 2020: Kaori stopped seeing Ruri and Seri in person, but kept in contact with the former. Around this time, Kaori started going in and out of the hospital, and realized she didn't have much time left. She began reading "Girls Lovers Suicide," but was devastated when Shizuku stopped updating it.
- April 6, 2020: Kaori saw Shizuku at the entrance ceremony and noticed that she was an entirely different person.
- July 15, 2020: The story begins. Shizuku finishes her novel, promptly deletes it and resolves to kill herself after throwing it away.
- July 16, 2020: On the second-to-last day before summer vacation, Shizuku attempts to throw her novel away, but Kaori picks up the novel and takes it home to read.
- July 17, 2020: On the last day before summer, Kaori tells Shizuku that she enjoyed the novel and encourages Shizuku to write another about their relationship.
- July 18, 2020: On the first day of summer vacation, Kaori visits Shizuku's house and meets her sister Shizuka.
- July 19, 2020: Kaori comes over in the morning and goes on a "library date" with Shizuku.
- July 25, 2020 A week after Kaori and Shizuku start dating, Kaori offers to go to the aquarium with Shizuku, who makes excuses. Around this time, Kaori's sister Shiori gives her morning glory seeds.
- July 26, 2020 The next day, Kaori comes over, having bought Shizuku some clothing. She also plants the morning glory seeds.
- July 27, 2020: Kaori and Shizuku go on an aquarium date and Shizuku buys Kaori a plushie. Overwhelmed with guilt, Shizuku confesses to being a bully but is shocked to learn that Kaori already knew about it, and runs home. Shizuku gets home, angrily brushes off her sister's concern and goes to bed.
- July 28, 2020, The next day, Shizuku falls ill with a fever. Kaori drops off a letter with Shizuka. Shizuka delivers to it to Shizuku, who apologizes for the previous day.
- July 29, 2020: Shizuku's fever goes down and she reads Kaori's letter and messages her. Kaori comes over that afternoon. Kaori tells Shizuku what she knew about her, and insists that Shizuku is a better person than she gives herself credit for. Around this time, Seri meets up with Ruri, and considers going out for curry with her, but realizes that curry brings back Ruri's trauma.
- July 30, 2020. Shizuku invites Kaori to the library and takes the bus over.
- July 31, 2020: Kaori and Shizuku go to a fireworks festival together, but Shizuku notices Kaori is not her usual self. After getting home, Kaori struggles to breathe.
- August 1, 2020: The morning glories, which were planted a week prior, started to sprout, and Kaori comes over to see them. Shizuka and Kaori get onto a First-Name Basis.
- August 2, 2020: Shizuku finishes her apology letter and shows it to Kaori.
- August 3, 2020: Ruri offers to meet with Shizuku and Kaori on August 7.
- August 7, 2020: Shizuku and Kaori meet with Ruri and Seri. Shizuku tries to apologize, but Ruri says she wants nothing more to do with Shizuku, and Shizuku accepts her decision. As Ruri and Seri are leaving, Kaori collapses. Ruri goes with Kaori in the ambulance, while Seri tells Shizuku about Kaori's illness.
- August 8, 2020: Shizuku visits Kaori in the hospital. Kaori tries to break up with Shizuku to not cause her pain, but Shizuku, unable to accept it, convinces Kaori to change her mind.
- August 9-10, 2020: Kaori undergoes tests and is unable to see Shizuku.
- August 11, 2020: Shizuku visits Kaori in the hospital and shows her the novel. She encounters Seri and Ruri on her way out, and Seri tells her more about Ruri and Kaori's illnesses.
- August 12, 2020: While visiting Kaori, Shizuku gets a text from Shizuka, prompting Kaori to propose that the two sisters go hiking.
- August 13, 2020: Shizuku and Shizuka go hiking on a mountain. During a conversation with her sister, Shizuku realizes how much her family cares about her.
- August 14, 2020: After visiting Kaori and telling her about the mountain hike, Shizuku visits the Asaka residence to get a book for Kaori. While talking with Kaori's sister, she realizes that she loves Kaori. That evening, Shizuka hears about an incoming typhoon and decides not to visit Kaori the next day.
- August 15, 2020: Shizuku talks with Kaori on the phone, and Kaori suggests getting matching promise rings.
- August 16, 2020: Shizuku, unable to afford a ring, buys a hair ribbon for Kaori. Ruri visits Kaori and shares that she knows Shizuku is changing.
- August 17, 2020: Shizuku visits Kaori to show her the latest progress, but becomes conflicted about writing an ending.
- August 18, 2020: Shizuku tries to visit Kaori. She learns from the Asakas that Kaori slipped into unconsciousness the previous night, and will be unable to see visitors. Kaori texts her to say that she will be available for visiting in two days.
- August 20, 2020: Shizuku, unable to make progress on her novel, declines to visit Kaori, and texts Kaori to say she will not be able to visit.
- August 21, 2020: Kaori calls Shizuku and begs her to visit, not wanting to die before she sees her again. Shizuku immediately comes over and apologizes. Kaori proposes going to the beach and sends Ruri an invitation.
- August 23, 2020: Kaori goes on an outing with Seri, Ruri and Shizuku. Kaori asks Ruri and Shizuku to get a drink, and Ruri expresses a desire to get to know Shizuku better. Seri and Ruri part ways with Kaori and Shizuku, who go back to the aquarium. Kaori tearfully confesses that she's scared of death and Shizuku tries to comfort her. Kaori goes home and sleeps in a bed with Shiori.
- August 24, 2020: Kaori returns to the hospital, and has tests done on her. Shizuku tells her about her previous novel, before vowing to finish the current one.
- August 27, 2020: Shizuku visits Kaori and finds out that she is not eating much. That evening, Shizuku finishes the novel, but gets a call from Seri informing her that Kaori's condition has taken a turn for the worse. Shizuku arrives at the hospital, finds that Kaori has a 50-50 chance of survival, and is so distraught Seri takes her home.
- August 28, 2020: Kaori regains consciousness, and has a heart-to-heart talk with Shizuku over text. Shizuku shows Kaori a picture of the nearly bloomed morning glories, then goes home and sends Kaori the last line of the novel, a Love Confession.
- August 29, 2020: Kaori sends Shizuku her final text, "Me too," around 1 in the morning, and passes away before Shizuku wakes up. Shizuku comes over, sees Kaori's dead body, and flees home, isolating herself in her room.
- September 4, 2020: Seri and Ruri come to the Hoshikawa house and get Shizuku to come to the Asaka house. Shizuku reads Kaori's diary and learns that Kaori has always admired her since Shizuku helped her in elementary school, and for being the author of "Girls Lovers Suicide." Shizuku, overwhelmed with emotion, breaks down in tears.
- September 5, 2020: Shizuku returns to school and greets her classmates, as Kaori has brought her out of her shell. The story ends.
