My Neighbor Seki

An original video animation by Shin-Ei Animation was released bundled with the limited edition of the manga's fifth volume on January 4, 2014, and a 21-episode anime adaptation aired in Japan between January and May 2014. A spin-off manga serialized from July 2020 to May 2023.

The series follows a girl named Rumi Yokoi who is constantly distracted by her neighboring classmate, Toshinari Seki, as he indulges in elaborate hobbies and somehow never gets caught in the process.

Rumi Yokoi (横井 るみ, Yokoi Rumi) Voiced by: Kana Hanazawa (Japanese); Monica Rial (English), Fumika Shimizu (live-action) Rumi is the viewpoint character and narrator of Seki's games. She continuously attempts to pay attention in class but is almost always distracted by her neighbor's antics. She sometimes tries to make Seki concentrate on class by sabotaging his projects, but usually finds herself joining in on them, though Seki misunderstands these attempts. Some episodes feature Rumi getting just as, if not more so, involved than Seki in his games, such as when he spends a day knitting or whenever he brings the Robot Family into school. In My Neighbour Seki-kun Junior, she marries Seki and they have a two-year-old son named Makuru. Toshinari Seki (関 俊成, Seki Toshinari) Voiced by: Hiro Shimono (Japanese); Blake Shepard (English), Yutaro Watanabe (live-action) Normally referred to by his surname, Seki is Rumi's classmate, and is a cheerful but mysterious character who is always playing games at his desk, which at times, include some elaborate setups. His activity bothers Rumi to no end, although he is almost never caught in the act by the teachers. In his desk is a complex array of objects that, if disturbed by anyone but himself, are impossible to put back together.[ch. 9] He rarely speaks, but is sometimes seen chatting with his friends. Despite his normal demeanor around his fellow students outside of the classroom, he is occasionally shown to have a dark and sadistic side. This comes through his destruction, sometimes wantonly, of his games and toys. He is also slightly superstitious, as is shown when some of his projects become so intense for Rumi that she secretly gets involved, scaring Seki out of his wits and his flippant behavior towards education. In My Neighbour Seki Junior, he marries Yokoi and have Makuru as their son.

Sakurako Gotō (後藤 桜子, Gotō Sakurako) is a girl who sits near Rumi and Seki during art class and becomes the former's friend. She assumes Seki and Rumi are lovers because of the way they interact in class. Regardless of any relationship Rumi and Seki may actually have or not have in the present or future, almost everything she assumes is entirely based on her own imagination.[ch. 22] Voiced by: Satomi Satō (Japanese); Caitlynn French (English). Portrayed by Rika Mayama in the live-action drama. Tomoka Hashino (橋野 友香, Hashino Tomoka) is Rumi's classmate with glasses. Voiced by: Kokoro Kikuchi (Japanese); Jad Saxton (English) Akiyasu Uzawa (宇沢 明康, Uzawa Akiyasu) is a laid-back classmate who is easily bored and often gets in the way of Seki's activities.[ch. 36] Voiced by: Minoru Shiraishi (Japanese); Corey Hartzog (English) Takahiro Maeda (前田 高広, Maeda Takahiro) is a male student who sits directly in front of Seki. Due to his height and large build, he blocks the teachers from noticing Seki's activities.[ch. 20] Voiced by: Shigeyuki Susaki Yū Nakama (仲間 由宇, Nakama Yū) is Rumi's classmate and friend. Voiced by: Mami Shitara (Japanese); Carolyn Medrano (English)

Written and illustrated by Takuma Morishige, the manga began as a one-shot published in the August 2010 issue of Media Factory's Comic Flapper magazine, and later started serialization in the magazine's November 2010 issue. The first tankōbon volume was published on April 23, 2011 and the tenth was released in March 2017. Vertical licensed the manga for North American publication under the title My Neighbor Seki, and has been releasing volumes since January 2015. A spin-off series titled My Neighbor Seki-kun Junior launched in the July 4, 2020, issue of Monthly Comic Flapper. The spin-off ended in the May 2, 2023, issue of Monthly Comic Flapper. The spin-off's chapters were collected into three tankōbon volumes from June 23, 2021, to June 22, 2023.

A 21-episode anime directed by Yūji Mutoh and produced by Shin-Ei Animation, aired in Japan between January 5 and May 25, 2014, and was simulcast by Crunchyroll under the title Tonari no Seki-kun: The Master of Killing Time. The fifth manga volume was released simultaneously on January 4, 2014, with a limited edition, bundled with an original animation DVD containing two additional episodes. The series was released on DVD in two parts on May 28, 2014, with a bonus episode on each disc. The opening theme is "Meiwaku Spectacle" (迷惑スペクタクル, Meiwaku Supekutakuru; lit. 'Nuisance Spectacle') by Kana Hanazawa, and the ending theme is "Set Them Free" by Akira Jimbo. The music in the series is composed by Akifumi Tada. The drama CD for the anime was released on January 22, 2014, by King Records.

The series was adapted into a live-action show where it was paired with another live-action adaptation titled Rumi's Phenomenon. Both programs involve a main character named Rumi. It premiered on MBS and TBS on July 27, 2015 as Tonari no Seki-kun to Rumi-chan no Jishō (となりの関くんとるみちゃんの事象; My Neighbor Seki and Rumi's Phenomenon) and ran for eight episodes. Morishige said "I feel a sense of odd destiny that the heroines' names are coincidentally the same."