Ongoing Manga · EN
Onii-chan wa Oshimai!
Also known as Onii-chan wa Oshimai!
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)
Start from the beginningChapter 1Read latestChapter 115
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CH.115Onii-chan wa Oshimai! Chapter 115Mahiro and the Joys of Creation · Sep 13, 2026 · 5 min0viewsCH.114Onii-chan wa Oshimai! Chapter 114Mahiro and the Cosplay Photoshoot · Sep 13, 2026 · 5 min0viewsCH.113Onii-chan wa Oshimai! Chapter 113Mahiro and the Ecological Research Duo · Sep 13, 2026 · 5 min0viewsCH.112.5Onii-chan wa Oshimai! Chapter 112.5MAHIRO AND THE SUCCUBUS DRESS · Sep 13, 2026 · 3 min0viewsCH.112Onii-chan wa Oshimai! Chapter 112Mahiro and Gender Topsy-Turvy · Sep 13, 2026 · 5 min0viewsCH.111.5Onii-chan wa Oshimai! Chapter 111.5MAHIRO AND THE SECOND ROUND · Sep 13, 2026 · 3 min0viewsCH.111Onii-chan wa Oshimai! Chapter 111Mahiro and the Fun-filled Lion's Den · Sep 13, 2026 · 6 min0viewsCH.110Onii-chan wa Oshimai! Chapter 110Mahiro and the Demon of the Prefect Council · Sep 13, 2026 · 4 min0viewsCH.109Onii-chan wa Oshimai! Chapter 109Mahiro and a Healthy Beauty Regimen · Sep 13, 2026 · 5 min0viewsCH.108.5Onii-chan wa Oshimai! Chapter 108.5A DATE WITH NEMU · Sep 13, 2026 · 2 min0viewsCH.108Onii-chan wa Oshimai! Chapter 108Mahiro and Bodyguards · Sep 13, 2026 · 5 min0viewsCH.107.9Onii-chan wa Oshimai! Chapter 107.9Minato-kun is Done For? 3 · Sep 13, 2026 · 9 min0viewsCH.107.5Onii-chan wa Oshimai! Chapter 107.5MAHIRO AND THE MAKEOVER · Sep 13, 2026 · 1 min0viewsCH.107Onii-chan wa Oshimai! Chapter 107Mahiro and Popularity Rankings · Sep 13, 2026 · 5 min0viewsCH.106Onii-chan wa Oshimai! Chapter 106Mahiro and Sharing Secrets · Sep 13, 2026 · 5 min0viewsCH.105Onii-chan wa Oshimai! Chapter 105Mahiro and an Offline Adventure · Sep 13, 2026 · 5 min0viewsCH.104.5Onii-chan wa Oshimai! Chapter 104.5MAHIRO AND THE MOTHERLY EMBRACE · Sep 13, 2026 · 2 min0viewsCH.104Onii-chan wa Oshimai! Chapter 104Mahiro and Mother's Day · Sep 13, 2026 · 5 min0viewsCH.103Onii-chan wa Oshimai! Chapter 103Mahiro and Heaven or Hell · Sep 13, 2026 · 5 min0viewsCH.102.2Onii-chan wa Oshimai! Chapter 102.2Aoi-chan Edition · Sep 13, 2026 · 2 min0viewsCH.102.1Onii-chan wa Oshimai! Chapter 102.1Niichi-chan Edition · Sep 13, 2026 · 1 min0viewsCH.102Onii-chan wa Oshimai! Chapter 102Mahiro and a Technological Nightmare · Sep 13, 2026 · 5 min0viewsCH.101.5Onii-chan wa Oshimai! Chapter 101.5MAHIRO AND THE FEMALE CHARACTERS · Sep 13, 2026 · 2 min0viewsCH.101Onii-chan wa Oshimai! Chapter 101Mahiro and a Celebration · Sep 13, 2026 · 5 min0viewsCH.100.9Onii-chan wa Oshimai! Chapter 100.9Onii-chan's Drawing Book · Sep 13, 2026 · 2 min0viewsCH.100.5Onii-chan wa Oshimai! Chapter 100.5MAHIRO AND THE CAT ARMY...... · Sep 13, 2026 · 5 min0viewsCH.100Onii-chan wa Oshimai! Chapter 100Mahiro and a Good Day for an Experiment · Sep 13, 2026 · 5 min0viewsCH.99.5Onii-chan wa Oshimai! Chapter 99.5Mahiro and Getting a License + Doujin Issue 33 Extras · Sep 13, 2026 · 3 min0viewsCH.99Onii-chan wa Oshimai! Chapter 99Mahiro and the Autobahn · Sep 13, 2026 · 5 min0viewsCH.98.5Onii-chan wa Oshimai! Chapter 98.5Mahiro and Being a Small Fry Human · Sep 13, 2026 · 1 min0viewsCH.98Onii-chan wa Oshimai! Chapter 98Mahiro and a One-Night Stay · Sep 13, 2026 · 5 min0viewsCH.97Onii-chan wa Oshimai! Chapter 97Mahiro and Crossing the Line · Sep 13, 2026 · 5 min0viewsCH.96Onii-chan wa Oshimai! Chapter 96Mahiro and a Token of Appreciation · Sep 13, 2026 · 5 min0viewsCH.95.9Onii-chan wa Oshimai! Chapter 95.9Minato-kun is Done For? 2 · Sep 13, 2026 · 10 min0viewsCH.95.5Onii-chan wa Oshimai! Chapter 95.5Miyo and the Date · Sep 13, 2026 · 3 min0viewsCH.95Onii-chan wa Oshimai! Chapter 95Mahiro and the University Expedition Squad · Sep 13, 2026 · 5 min0viewsCH.94Onii-chan wa Oshimai! Chapter 94Mahiro and the New School Year, Once Again · Sep 13, 2026 · 6 min0viewsCH.93.5Onii-chan wa Oshimai! Chapter 93.5The Boys and Another Shot · Sep 13, 2026 · 2 min0viewsCH.93Onii-chan wa Oshimai! Chapter 93Mahiro and a Special Treat · Sep 13, 2026 · 5 min0viewsCH.92.5Onii-chan wa Oshimai! Chapter 92.5Asahi and Growth · Sep 13, 2026 · 1 min0viewsCH.92Onii-chan wa Oshimai! Chapter 92Mahiro and a Maiden's Secret · Sep 13, 2026 · 5 min0viewsCH.91.5Onii-chan wa Oshimai! Chapter 91.5Nemu and Nodoka · Sep 13, 2026 · 1 min0viewsCH.91Onii-chan wa Oshimai! Chapter 91Mahiro and Marriage · Sep 13, 2026 · 5 min0viewsCH.90.9Onii-chan wa Oshimai! Chapter 90.9Volume 9 Special Edition Extras · Sep 13, 2026 · 1 min0viewsCH.90.8Onii-chan wa Oshimai! Chapter 90.8Mahiro and Mama (Revisited) · Sep 13, 2026 · 3 min0viewsCH.86.5Onii-chan wa Oshimai! Chapter 86.5Special: Asahi's Birthday · Sep 13, 2026 · 2 min0viewsCH.81.8Onii-chan wa Oshimai! Chapter 81.8Non-Mahiro Special: Aoi-chan Edition · Sep 13, 2026 · 2 min0viewsCH.74Onii-chan wa Oshimai! Chapter 74Mahiro and a Night Together · Sep 13, 2026 · 5 min0viewsCH.73.5Onii-chan wa Oshimai! Chapter 73.5Non-Mahiro Special: Nii-chan Edition · Sep 13, 2026 · 1 min0viewsCH.01Onii-chan wa Oshimai! Chapter 1Mahiro and the Unpleasurable Body · Sep 13, 2026 · 5 min0views
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