Webcomic

Nagatoro-san (長瀞さん), is a Japanese webcomic series written and illustrated by Nanashi. It was published between August 15, 2011, and December 25, 2015, on as doujins prior to the serialization of the manga Ijiranaide, Nagatoro-san, which is loosely based on it.

Out of all the issues, three are narrated in a first-person perspective from the reader's point of view, due to the protagonist having conversations with Nagatoro while directly facing her. Only in the third issue the reader has a third-person perspective, while the fifth is done in a classic manga style and was later published in the Illust Collection as a special chapter.

Story
A shy and spineless high schooler, Hachiouji, falls in love with a sadistic younger girl called Hayase Nagatoro who loves to torture, humiliate and abuse him both physically and emotionally. Each issue follows their bizarre "lovey-dovey" growing relationship.

Characters

 * Hayase Nagatoro, the sadistic love interest of Hachioji senpai.
 * Hachiouji, a high school student, in love with Nagatoro.
 * Ichirō Nagatoro, the protagonist's older brother.

Differences with the manga

 * The main difference is Nagatoro's cruelty: while in the manga she's a somewhat innocent girl which is evidently very shy and sweet under all her teasing, and goes too far only accidentally in the first two chapters before toning down her taunts towards Senpai sine she doesn't actually want to hurt him; in the webcomic, Nagatoro is a malicious sadist who evidently gains pleasure by hurting others, is violently abusive both physically and emotionally towards Hachiouji, to the point she mind-breaks him into an anguished declaration of love, and rarely apologized to him or shows any signs of caring.
 * Nagatoro and Hachiouji are an established couple since the end of the first issue.
 * Hachiouji doesn't wear glasses, looking less of a stereotypical nerd. Also, he exhibits some masochist tendencies, often showing to find pleasure in the pain Nagatoro inflicted on him.
 * While he remained nameless for most of the first part of the manga, in the webcomic Senpai's family name, Hachiouji, is revealed since the first issue.
 * The age of the characters and which school year they attend are not mentioned.
 * It's unclear which sports club Nagatoro is part of.
 * Although not clearly specified, the story spans several years, as in the fourth issue Nagatoro has visibly grown up.
 * In the manga Nagatoro's brother is a mostly unseen character until Chapter 93; also, after first meeting Senpai, he hides his real identity from him in order to fuel the misunderstanding of the latter, who believed him to be Hayase's ex-boyfriend, and test his feelings for his sister; while in the webcomic he is the only other character excluding the protagonists and it was his sister who hid his identity to Hachiouji in order to pull a cruel prank on him.
 * The first name of Nagatoro's brother was changed from Ichirō to Taiga in the manga.