Official Introduction: Now approaching you is: Muzan's nightmare, the destroyer of the Twelve Demon Moons, the head of the Infinity Castle demolition office, the most righteous person in the Demon Slayer Corps, Sabito's savior, the eternal absentee of Kanae Kocho's tea party, Giyu's good senior brother, the founder of Fist Breathing, and a grandmaster.

Willow branches provide shade, that's it!

Kanae Kocho: "I invited him to a tea party ninety-seven times, and he refused ninety-seven times. He's so gentle."

Shinobu Kocho: "Why should I be trained by iron fists? It's infuriating, sister!"

Akaza: "A powerful person, the best in physical combat."

Muzan Kibutsuji: "A monster who destroyed all my Demon Moons with his bare hands and blasted the Infinity Castle to pieces, you call him human?!"

Unofficial synopsis: Yagyu In transmigrates to the world of Demon Slayer, but the system believes he is in the world of One Piece and identifies him as a Marine.

You can earn Navy Points and rewards by doing things that are in line with the Navy's rules.

Yagyu In: No, buddy, is this right? Where did this pirate from the Demon Slayer world come from that I need to catch?!

Pirates are attacking! Strike immediately to capture or kill them!

Looking at the man-eating ghost before him, Liu Shengyin realized that the system had gone mad.

From then on, the Demon Slayer Corps had one more instructor who liked to smash people's heads with his iron fist of love.

This book is also known as "Left Fist's Overpowering Entanglement Deals High Damage, Right Fist's Overpowering Entanglement Deals High Damage," "Three Punches Shatter Evil Spirits, Sir, I'm Just an Ordinary Person," "Overpowering Aura is Also Qi, and Qi is Breathing Technique!" and "Muzan, Are You Hiding Well? The Marine Admiral is Coming to Get You~"

Note: This book is a crossover anime/manga series, and will later explore other worlds.

What to do when you're out at sea without a ship? Allen: "Steal someone else's." What to do when there's no one on board? Allen: "Dig someone else's." What to do when there are people but no supplies? Allen: "Rob a warship." Treasure, famous swords, Devil Fruits, where do the women come from? Allen: "Brothers, look! There's a transport ship that's practically floating on air, it has everything!"... Transmigrating to the world of One Piece, relying on Baki's cheat abilities to rise to power in the East Blue, starting with just his fists, he steals everything—people and ships. My name is Allen, and I advocate for freedom. (A million-word completed high-quality One Piece fanfiction is already available; readers are welcome to jump in and get crazy!)