Onii-chan wa Oshimai!
Nekotoufu
Ongoing2017
Synopsis
Mahiro Oyama was just a normal erotic-game loving dude...until he woke up one morning as a woman! Turns out his mad-scientist little sister, Mihari, tried out one of her new experiments on him...with a disastrous outcome, as far as Mahiro's concerned! But Mihari is as determined to study him as he is determined to go back to his shut-in, game-playing life, and one thing's for sure...life is going to get a whole lot weirder from here on out! *5th place of Tsugi Manga Awards, Category Webmanga - **Retail:** (Direct Retail From the Mangaka)  [Official Melon Books](https://www.melonbooks.co.jp/circle/index.php?circle_id=3753)  [Official Toranoana](https://ec.toranoana.shop/tora/ec/cot/circle/2UPA116P847KdC6Rd687/all/)  [Official DLSite](https://www.dlsite.com/home/circle/profile/=/maker_id/RG40614.html) (jp)
208+
Chapters
—
Rating
2017
Year
Chapters(208 loaded)
Ch. 110Mahiro and the Demon of the Prefect Council
Mar 27, 2026Ch. 109Mahiro and a Healthy Beauty Regimen
Feb 27, 2026Ch. 108.5 A DATE WITH NEMU
Apr 10, 2026Ch. 108Mahiro and Bodyguards
Jan 31, 2026Ch. 107.9Minato-kun is Done For? 3
Jan 10, 2026Ch. 107.5MAHIRO AND THE MAKEOVER
Apr 10, 2026Ch. 107Mahiro and Popularity Rankings
Dec 27, 2025Ch. 106Mahiro and Sharing Secrets
Nov 29, 2025Ch. 105Mahiro and an Offline Adventure
Oct 24, 2025Ch. 104.5MAHIRO AND THE MOTHERLY EMBRACE
Apr 10, 2026Ch. 104Mahiro and Mother's Day
Sep 26, 2025Ch. 103Mahiro and Heaven or Hell
Aug 30, 2025Ch. 102.2Aoi-chan Edition
Oct 31, 2025Ch. 102.1Niichi-chan Edition
Oct 31, 2025Ch. 102Mahiro and a Technological Nightmare
Jul 25, 2025Ch. 101.5MAHIRO AND THE FEMALE CHARACTERS
Apr 10, 2026Ch. 101Mahiro and a Celebration
Jun 27, 2025Ch. 100.9Onii-chan's Drawing Book
Nov 1, 2025Ch. 100Mahiro and a Good Day for an Experiment
May 30, 2025Ch. 99.5Mahiro and Getting a License + Doujin Issue 33 Extras
Jul 8, 2025Ch. 99Mahiro and the Autobahn
Apr 25, 2025Ch. 98.5Mahiro and Being a Small Fry Human
Jul 8, 2025Ch. 98Mahiro and a One-Night Stay
Mar 28, 2025Ch. 97Mahiro and Crossing the Line
Feb 22, 2025Ch. 96Mahiro and a Token of Appreciation
Jan 25, 2025Ch. 95.9Minato-kun is Done For? 2
Jan 1, 2025Ch. 95.5Miyo and the Date
Mar 1, 2025Ch. 95Mahiro and the University Expedition Squad
Dec 28, 2024Ch. 94Mahiro and the New School Year, Once Again
Nov 30, 2024Ch. 93.5The Boys and Another Shot
Jan 11, 2025Ch. 93Mahiro and a Special Treat
Oct 26, 2024Ch. 92.5Asahi and Growth
Jan 11, 2025Ch. 92Mahiro and a Maiden's Secret
Sep 27, 2024Ch. 91.5Nemu and Nodoka
Jan 11, 2025Ch. 91Mahiro and Marriage
Aug 31, 2024Ch. 90.9Volume 9 Special Edition Extras
Oct 19, 2024Ch. 90.8Mahiro and Mama (Revisited)
Oct 19, 2024Ch. 90.5Chapter 90.5
Aug 16, 2024Ch. 90Mahiro and Celebrating Success
Jul 27, 2024Ch. 89Mahiro and a Home Visit
Jun 29, 2024Ch. 88.5Chapter 88.5
Aug 16, 2024Ch. 88Mahiro and Romantic Antics
May 24, 2024Ch. 87Mahiro and Special Techniques
Apr 26, 2024Ch. 86.9Minato-kun is Done For? 1.5
Apr 10, 2024Ch. 86.5Special: Asahi's Birthday
Sep 20, 2024Ch. 86Mahiro and Overflowing Maternal Instincts
Mar 29, 2024Ch. 85.5Chapter 85.5
May 31, 2024Ch. 85Mahiro and a Stressful Reunion (Part 2)
Feb 24, 2024Ch. 84Mahiro and a Stressful Reunion (Part 1)
Jan 27, 2024Ch. 83.9Minato-kun is Done For? (Full Version)
Jan 6, 2024Ch. 83Mahiro and the New Year's Tour
Dec 31, 2023Ch. 82.5Chapter 82.5
Mar 2, 2024Ch. 82Mahiro and a Silent Night
Nov 25, 2023Ch. 81.9Minato-kun is Done For? (Preview Version)
Nov 11, 2023Ch. 81.8Non-Mahiro Special: Aoi-chan Edition
Nov 4, 2025Ch. 81.5Chapter 81.5
Jan 2, 2024Ch. 81Mahiro and Conflicting Views
Oct 28, 2023Ch. 80.8Mahiro and the Growing Gal Gang + Volume 8 Extras
Dec 9, 2023Ch. 80Mahiro and the Secret Engagement
Sep 30, 2023Ch. 79Mahiro and the Gal Gang
Aug 26, 2023Ch. 78.9Mihari's Research Lab
Aug 15, 2023Ch. 78.5The Boys and MMORPGs
Aug 14, 2023Ch. 78Mahiro and MMORPGs Revisited
Jul 29, 2023Ch. 77Mahiro and the Farewell Party
Jun 24, 2023Ch. 76.9The Research Lab's Mihari-chan
Jun 4, 2023Ch. 76.1Blu-Ray Box Volume 2 Add-in Comic
Jun 22, 2023Ch. 76Mahiro and a Close Call
May 27, 2023Ch. 75Mahiro and the Siren's Call
Apr 29, 2023Ch. 74.99Mihari's Birthday Venue
Apr 21, 2023Ch. 74.5Everyone and the Blackout
May 5, 2023Ch. 74.1Blu-Ray Box Volume 1 Add-in Comic
Apr 20, 2023Ch. 74Mahiro and a Night Together
Jul 5, 2025Ch. 73.5Non-Mahiro Special: Nii-chan Edition
Nov 6, 2025Ch. 73.1Mahiro-chan's Birthday Venue (2023)
Apr 11, 2023Ch. 73Mahiro and Big Bro's Secrets
Mar 20, 2023Ch. 72.9The Boys Are Done For Too! + Omnibus 22-23-24 Extras
Aug 15, 2024Ch. 72Mahiro and an Admiration
Feb 20, 2023Ch. 71.5Mahiro and the Magazine Model
Mar 29, 2023Ch. 71Mahiro and the selfie boom
Jan 18, 2023Ch. 70.9Volume 7 Special Booklet
Apr 7, 2023Ch. 70.8Volume 7 Extras
Mar 23, 2023Ch. 70.7Mahiro and a Discussion on Cosplay
Mar 23, 2023Ch. 70Mahiro and an autumn outing
Dec 13, 2022Ch. 69.99Nayutan's Birthday Venue
Apr 11, 2023Ch. 69.5Mahiro and a Moment of Glory
Mar 22, 2023Ch. 69Mahiro and the Youthful Sports Festival
Nov 14, 2022Ch. 68.99Momiji Birthday Venue
Apr 11, 2023Ch. 68Mahiro and the World of Hobbies
Oct 19, 2022Ch. 67.99Kaede-chan's birthday venue
Apr 11, 2023Ch. 67Mahiro and Male Pride
Sep 11, 2022Ch. 66.5The Boys and Changing Shifts
Mar 22, 2023Ch. 66Mahiro and the Tempting Culture Festival (Part 2)
Aug 3, 2022Ch. 65Mahiro and the Tempting Culture Festival (Part 1)
Jun 29, 2022Ch. 64Mahiro and a Healthy Diet
Jun 28, 2022Ch. 63.99Omnibus 19-20-21 Extras
Aug 28, 2023Ch. 63.5Momiji and Panties
Mar 22, 2023Ch. 63Mahiro and Staying Over Because of Rain
Apr 30, 2022Ch. 62.5Nemu and Summer Vacation
Mar 22, 2023Ch. 62.1Mihari-chan's Birthday Venue
Apr 11, 2023Ch. 62Mahiro and a 2nd Semester Debut
Mar 27, 2022Ch. 61Mahiro and Summer Festival
Feb 28, 2022Ch. 60Mahiro and Summer Homework
Feb 12, 2022Ch. 59Mahiro and spring cleaning
Jan 28, 2022Ch. 58Mahiro and the Marine Ranger (Part 2)
Nov 27, 2021Ch. 57Mahiro and the Marine Ranger (Part 1)
Oct 31, 2021Ch. 56Mahiro and The Battle Plan Meeting
Oct 12, 2021Ch. 55Mahiro and a Summer Adventure
Aug 30, 2021Ch. 54.9Omnibus 16-17-18 Extras
May 27, 2023Ch. 54.7Mahiro and Harems
May 17, 2023Ch. 54.5Mahiro and the serene mind
Dec 17, 2023Ch. 54Mahiro and School Ghost Stories
Jul 26, 2021Ch. 53.5Boys and Girls
Aug 16, 2021Ch. 53Mahiro and the North Wind and Sun
Jul 7, 2021Ch. 52Mahiro and the Little Garden
Jul 7, 2021Ch. 51Mahiro and Passing the Rainy Season
Jul 7, 2021Ch. 50.5Chapter 50.5
Jul 7, 2021Ch. 50Mahiro and Swim Classes (Part 2)
Jul 7, 2021Ch. 49Mahiro and Swim Classes (Part 1)
Feb 24, 2021Ch. 48.5MAHIRO AND THE PARENT-TEACHER CONFERENCE
Dec 19, 2023Ch. 48Mahiro and Class Observation
Feb 17, 2021Ch. 47Mahiro and the Sunny Girl
Dec 27, 2020Ch. 46.5Mihari and Memories of Stickers
Aug 5, 2021Ch. 46Mahiro and Sticker Collecting (fixed)
Nov 28, 2020Ch. 45.9Omnibus 13-14-15 Extras
May 25, 2023Ch. 45.7Mahiro and Visible Undergarments
May 20, 2023Ch. 45Mahiro and the Season for New Clothes
Nov 9, 2020Ch. 44Mahiro and the Secret BBQ
Oct 5, 2020Ch. 43.5Chapter 43.5
Aug 5, 2021Ch. 43Mahiro and Fragrances
Aug 31, 2020Ch. 42.6EX3 Special - Mahiro and a Hair's Breadth from Danger!
Aug 31, 2020Ch. 42.5[TEMP 1]41.3+41.7 & 42.5 & Mini Extra (2 of 10)
Aug 30, 2020Ch. 42Mahiro and the Gift of Memories
Jul 26, 2020Ch. 41Mahiro and the Physical Examination
Jun 27, 2020Ch. 40.99Bonus Illustration
Aug 30, 2020Ch. 40.8Mihari and Skipping Grades
Aug 30, 2020Ch. 40.6Mini Extras [Complete]
Aug 30, 2020Ch. 40.5Mahiro and Barefoot
Aug 30, 2020Ch. 40Mahiro and an Important Secret (Part 2)
May 24, 2020Ch. 39Mahiro and an Important Secret
Apr 25, 2020Ch. 38.5Momiji and Massages
Aug 30, 2020Ch. 38Mahiro and an Appreciated Break
Apr 9, 2020Ch. 37.5Mihari and High School Girls
Aug 30, 2020Ch. 37Mahiro and a Girl's Mannerisms
Feb 28, 2020Ch. 36.9Mahiro's Weekday Routine + Omnibus 10-11-12 Extras
May 25, 2023Ch. 36.5Mahiro and a Present
Aug 30, 2020Ch. 36Mahiro and a Surprise
Jan 29, 2020Ch. 35.6EX2 Special - I am Mahiro and I am Mihari
Jan 19, 2020Ch. 35Mahiro and the Guidance of Fortunes
Dec 29, 2019Ch. 34.5Chapter 34.5 (1+2+3)
Aug 30, 2020Ch. 34Mahiro and the Adult's Door
Dec 1, 2019Ch. 33.5Mahiro and Handmade
Aug 30, 2020Ch. 33Mahiro and Valentine's
Oct 29, 2019Ch. 32.5Mahiro and Drinks
Aug 30, 2020Ch. 32Mahiro and a Surprise Visit
Sep 28, 2019Ch. 31Mahiro and Charming Bare Legs
Sep 28, 2019Ch. 30.9Chapter 21-30 Mini Extras [Complete]
Dec 3, 2019Ch. 30.8Asahi and Momiji
Dec 3, 2019Ch. 30.5Mahiro and Hot Kiss
Aug 8, 2019Ch. 30Mahiro and the Coming and Going Year
Jul 31, 2019Ch. 29Mahiro and a Double Date
Jun 29, 2019Ch. 28.1Mahiro and Girl's Night (Second Part) [Tank Version]
Dec 3, 2019Ch. 28Mahiro and Girl's Night (Second Part) [Pixiv Version]
May 28, 2019Ch. 27.99Omnibus 7-8-9 Extras
May 25, 2023Ch. 27.5Including Extra (25.5 - 26.5 - 27.5)
May 26, 2019Ch. 27Mahiro and Girl's Night (First Part)
Apr 27, 2019Ch. 26Mahiro and Patissier
Mar 31, 2019Ch. 25Mahiro and Finals
Feb 27, 2019Ch. 24.5Part 1: Mahiro and Bento & Part 2: Mihari and Bento
May 26, 2019Ch. 24Mahiro and Common Interests
Feb 1, 2019Ch. 23Mahiro and the Fun Weekend
Dec 30, 2018Ch. 22.5EX Special - Mahiro and an Uneventful Holiday
May 26, 2019Ch. 22Mahiro and the Harsh Lesson
Nov 26, 2018Ch. 21.5Extras
May 25, 2019Ch. 21Mahiro and the First Day of School (V2)
Oct 31, 2018Ch. 20.9Chapter 11-20 Mini Extras
May 24, 2019Ch. 20.5Mihari and Dresses + Mihari (afterwards) and Dresses
May 25, 2019Ch. 20Mahiro and Middle Schoolers (v2)
Oct 4, 2018Ch. 19Mahiro and Uploading Videos
Aug 31, 2018Ch. 18.99Omnibus 4-5-6 Extras
May 20, 2023Ch. 18.5Part 1: Mahiro and a "Comrade's" Return & Part 2: Mahiro and Perms
May 25, 2019Ch. 18Mahiro and the Onsen Panic (Second Part)
Jul 30, 2018Ch. 17Mahiro and the Onsen Panic (First Part)
Jul 7, 2018Ch. 16Mahiro and the Hair Salon
May 27, 2018Ch. 15.5Siblings and Kotatsu
May 25, 2019Ch. 15Mahiro and Party Night
Apr 30, 2018Ch. 14Mahiro and a Little Adventure
Apr 3, 2018Ch. 13Mahiro and a Wholesome Relationship
Mar 1, 2018Ch. 12.5Mahiro and Nichiasa
May 24, 2019Ch. 12Mahiro and a Lonely Night
Feb 4, 2018Ch. 11Mahiro and Adventure
Feb 4, 2018Ch. 10.99Omnibus 1-2-3 Extras
May 17, 2023Ch. 10.9Chapter 1-10 Mini Extras
May 24, 2019Ch. 10.5Mahiro and Helping Out & OMAKE - Mihari and Onii-chan
Jul 21, 2018Ch. 10Mahiro and Special Home Security
Feb 3, 2018Ch. 9.5Mahiro and the Two's Secret
Jul 21, 2018Ch. 9Mahiro and a Girl's Vacation
Feb 3, 2018Ch. 8.5Mahiro and Gacha (v2)
Feb 6, 2018Ch. 8Mahiro and New Game
Feb 2, 2018Ch. 7Mahiro and Encounters with the Unknown
Feb 2, 2018Ch. 6.5Mahiro and Going in Circles
Jul 21, 2018Ch. 6Mahiro and the Secret Garden
Jan 31, 2018Ch. 5.5Mahiro and Comfort for Many Days
Jul 21, 2018Ch. 5Mahiro and a Melancholic Day
Jan 31, 2018Ch. 4Mahiro and MMORPG
Jan 30, 2018Ch. 3Mahiro and Identity
Jan 30, 2018Ch. 2Mahiro and the Dangerous Mirror
Jan 29, 2018Ch. 1.5Mahiro and the Toilet
Jul 21, 2018Ch. 1Mahiro and the Unpleasurable Body
Jan 29, 2018