Makkachin is first seen in a photo with Victor in a magazine that Yuuko shows to Yuuri when they are both children. This becomes Yuuri's inspiration to adopt a poodle, which he names Victor, nicknamed Vicchan. When Victor watches Yuuri's viral skating video of Stay Close to Me, Makkachin keeps Victor company on the sofa. Later on, when Yuuri's mother asks Yuuri to shovel snow, Yuuri opens the front door only to be knocked down by Makkachin. A surprised Yuuri mistakes Makkachin for Vicchan at first, until he realises the poodle in front of him is a lot bigger. Yuuri questions his father over this, who mentions that Makkachin was brought to Yu-topia Katsuki by a handsome foreign guest, which Yuuri guesses correctly to be Victor.
Minako finds Victor and Makkachin asleep together in the living room. When Victor wakes up, he wakes Makkachin at the same time by carrying the poodle. Makkachin huddles under the table while Victor eats, and later follows Victor to the new room. In days following that, Makkachin follows Victor and Yuuri for morning runs and physical training outside the rink, and is eventually also joined by Yuri Plisetsky when the latter comes to Japan in search of Victor.
Makkachin makes a short appearance, sitting beside Victor who is voraciously eating dinner. After Yuuri's sudden announcement that Eros is best represented by katsudon, he goes out running in embarrassment, who is accompanied by Makkachin.
Makkachin sleeps together with Yuuri, and wakes when Yuuri rushes out of the room for training. When Yuuri is burdened with guilt from being unable to pick his free skate song, Victor brings Yuuri to the beach along with Makkachin. After the Grand Prix series assignments are explained by the Nishigori triplets, Victor asks Makkachin to take care of the house during the season, to which Makkachin responds to with a lick on Victor's cheek.
Makkachin only appears once at the start of the episode, with Victor advising the poodle not to eat any manjū (sticky buns), then hugging Makkachin before leaving.
Makkachin is seen in a short clip, salivating over a plate of manjuu (sticky buns) left out on the table in front of the family shrine. At the end of the episode, half the plate of manjuu is gone, with the wrappers ripped open. Mari calls Yuuri to inform him and Victor that Makkachin had consumed the manjuu and choked on them. The Katsuki family had brought Makkachin to the vet for an operation, but Mari is worried that Makkachin would not be able to pull through. Yuuri, reminded of Vicchan's death, urges Victor to return to Japan to watch over Makkachin's operation.
A snippet of Episode 8 appears, where Mari informs Yuuri about Makkachin having choked on manjū. Victor departs for Japan to take care of Makkachin, leaving Yuuri behind in Moscow with Yakov as Yuuri's coach for one day. When Yuuri finally returns to Japan, a fully-recovered Makkachin is the first to spot Yuuri at the airport, allowing Victor and Yuuri to notice each other. Makkachin stays by Victor's side when Victor and Yuuri reunite in tears.
Makkachin appears in Victor's flashback when he mentions being happy that he was able to spend so much time with Makkachin while in Hasetsu.
After Yuuri's short program, Makkachin is seen in a flashback of Victor's. Makkachin tries to comfort Victor, who hugs the poodle in return; the monologue revealing that Victor had always thought he would be able to find new strength alone, but later realising that he was able to feel new emotions through Yuuri.
Makkachin sits alongside the Katsuki family, the Nishigori family and Kenjirou during the public viewing of the Barcelona GPF free skate at Yu-topia Katsuki.
At the end of the episode, Makkachin is seen running alongside Yuuri on the streets of Saint Petersburg. Makkachin barks upon seeing Victor and Yuri, such that it causes Yuuri to notice them as well.