__Occupation:__ Novelist

Itsuki is the protagonist of the series who has an obsession towards younger sisters. He is a novelist who debuted when he was in high school; all of his novels feature younger sisters as the heroine. In the span of five years, he has published 20 books, some of which have ranked in the top 10 weekly rankings for light novels on Oricon. Despite his success, his irrational personality and writing style has led to mediocre success compared to his fellow writers.

~!He admits to having feelings for Nayuta Kani, but he won't go out with her until he becomes her equal instead of living in her shadow.!~

~!His relationship with his father became worse when his father remarried to Chihiro's mother only 3 years after Itsuki's mother died.!~

The story follows the everyday life of Itsuki, a novelist and "modern day Pygmalion" who works day in and day out to create the ultimate younger sister. He's surrounded by various other characters: a beautiful genius writer who loves him, his big-sisterly classmate from college, a fellow male writer, a sadistic tax accountant, and his editor. They're all looked after by Itsuki's perfect younger step-brother, Chihiro, who has a serious secret. 
 
(Source: Anime News Network) 
 
Note: The first episode received an early screening at a special event held at Shinjuku Piccadilly, Tokyo on 06.09.2017.

__Height:__ 164 cm
__Hobbies:__ darts, driving, games, karaoke
__Skills & Abilities:__ acrobatics, karate, singing

[Profile (YU-RIN Pro)](https://yu-rin.com/pro-man/kobayashi-yusuke) | [Twitter](https://twitter.com/yusuke032510)

On January 1st, 2025, it was announced that he had gotten married to voice actress [Yumi Uchiyama](https://anilist.co/staff/106784/Yumi-Uchiyama).

__Non-Anime Roles:__
~! - Arslan in "Arslan Senki x Musou" (VG) (Japanese)
- Itaku in "Utawarerumono: Futari no Hakuoro" (VG) (Japanese)
- Opoona in "Warriors All-Stars" (VG) (Japanese)
- Ranmaru Mori in "Sengoku Night Blood" (VG) (Japanese)
- Sigurd in "Guardian's Violation" (VG) (Japanese)
- Takeru Akabane in "Code of Joker Edge" (arcade game) (Japanese)
- Terumi Niida; Kaoru Shishibara in "Prince of Stride" (VG) (Japanese)
- Tokugawa Ieyasu in "Hana Oboro ~Sengoku Den Ranki~" (VG) (Japanese)
- Tōshirō Shinano in "Touken Ranbu -ONLINE-" (VG) (Japanese) 
- Byleth in "Fire Emblem Three Houses-" (VG) (Japanese)
- Kalpas in "Honkai Impact 3rd" (VG) (Japanese)
- Xavier in "Love and Deepspace" (VG) (Japanese)!~

[Website](https://www.stephenfu.com/) | [Twitter](https://twitter.com/thatstephenfu)

Itsuki Hashima is a novelist who's hopelessly enamored with the idea of little sisters and is constantly surrounded by colorful characters. A world class genius and love-guru who's beauty almost seems a waste on her. A girl who's constantly troubled by her friendships, love interests, and can't even find refuge in her dreams. A ridiculously talented illustrator. Each of them have as many problems and worries as the next and they never have a dull day together as they play games, travel, and work together. From the same author of the famous I Don't Have Many Friends, Yomi Hirasaka!
 
(Source: Yen Press)

Original "chibi" styled animations of Imouto sae Ireba Ii. posted on the anime's official Twitter.

Itsuki Hashima is a novelist who's hopelessly enamored with the idea of little sisters and is constantly surrounded by colorful characters. A world class genius and love-guru who's beauty almost seems a waste on her. A girl who's constantly troubled by her friendships, love interests, and can't even find refuge in her dreams. A ridiculously talented illustrator. Each of them have as many problems and worries as the next and they never have a dull day together as they play games, travel, and work together. From the same author of the famous I Don't Have Many Friends, Yomi Hirasaka!
 
(Source: Yen Press)
 
Note: Includes four extra chapters.

Original "chibi" styled animations exclusively on volumes of the Imouto sae Ireba Ii. Blu-ray/DVD.