Moon Breathing (月の呼吸,Tsuki no kokyū?) is a Breathing Style derived from the Sun Breathing used by Upper Rank 1, Kokushibo, who was one of the first Demon Slayers who utilized breathing techniques. The techique allows the user to create many "chaotic blades" when slashing that vary in length and size. It is known that Kokushibo continued to develop and add techniques to the Breathing Style over the centuries as an immortal Demon. At this point in the story, it is the only known Breathing Style to possess at least 16 different techniques, easily surpassing the other Breathing Styles.
It has been revealed that, like all of the other original breathing styles, the Moon Breathing also branched out of the Sun Breathing. When its creator, Michikatsu Tsugikuni, attempted to learn the Sun Breathing from his twin brother, Yoriichi Tsugikuni, he discovered he was unable to master the breathing style and so was instead trained in a alternate Breathing Style. Yoriichi created it fit and cover his individual strengths and weaknesses, and Michikatsu then continued to train and develop this breathing until it eventually evolved into its own unique Breathing Style, which he named named Moon Breathing.
First Form: Dark Moon - Evening Palace (壱ノ型闇月・宵の宮,Ichi no kata: Yamitsuki - Yoi no Miya?) - Kokushibo draws his sword and slashes swiftly in a single motion; like with all Moon Breathing techniques, numerous chaotic blades originate from the slash. This technique resembles Iaido.
Second Form: Pearl Flowers Moongazing (弐の型珠華ノ弄月,Ni no kata: Shuka no Rōgetsu?) - Kokushibo performs several slashes while sending a barrage of chaotic blades forward.
Third Form: Loathsome Moon - Chains (参ノ型厭忌月・銷り,San no kata: Enkizuki - Tsugari?) - Kokushibo swings his sword rapidly in two crescent slashes, from which a storm of smaller crescents spread. This technique causes huge destruction in a small area.
Fifth Form: Moon Spirit Calamitous Eddy (伍ノ型月魄災渦,Go no kata: Geppaku Saika?) - Kokushibo makes multiple curved slashes layered over one another, resembling a rising vortex. Numerous chaotic blades originate from these slashes. Kokushibo performed this attack without swinging his blade.
Sixth Form: Perpetual Night, Lonely Moon - Incessant (陸ノ型常夜孤月・無間,Roku no kata: Tokoyo Kogetsu - Muken?) - Kokushibo releases a wild storm of slashes in multiple directions. This technique was powerful enough to not only slice up multiple Hashira around him but also overwhelm the Wind Hashira Sanemi Shinazugawa.
Seventh Form: Mirror of Misfortune - Moonlit (漆ノ型厄鏡・月映え,Shichi no kata: Yakkyō - Tsukibae?) - Kokushibo swings his sword in a powerful frontal slash that then creates a multi directional frontal assault, powerful enough to create several deep gouges in the ground and push back two Hashira.
Eighth Form: Moon-Dragon Ringtail (捌ノ型月龍輪尾,Hachi no kata: Getsuryū Rinbi?) - Kokushibo uses a direct frontal attack that creates a single gigantic slash.
Ninth Form: Waning Moonswaths (玖ノ型降り月・連面,Ku no kata: Kudaritsuki - Renmen?) - Kokushibo creates a seemingly endless stream of slashes, capable of cutting down his intended target from a long range.
Tenth Form: Drilling Slashes - Moon Through Bamboo Leaves (拾ノ型穿面斬・蘿月,Jū no kata: Senmenzan - Ragetsu?) - Kokushibo creates a triple-layered slash twister, capable of mowing down his targets into three clean pieces.
Fourteenth Form: Catastrophe - Tenman Crescent Moon (拾肆ノ型兇変・天満繊月,Jūshi no kata: Kyōhen - Tenman Sengetsu?) - Kokushibo swings his sword and creates a chaotic vortex of powerful omni-directional slashes that destroys whatever is caught up within its attack radius.
Sixteenth Form: Moonbow - Half Moon (拾陸ノ型月虹・片割れ月,Jūroku no kata: Gekkō - Katawaretsuki?) - Kokushibo swings his sword in a downward slash, resulting in a powerful sixfold slash crashing down on his opponents; the attack itself is powerful enough to create several miniature craters where the slashes have landed.