A magical girl located in the Saga Prefecture. She works with Kizutaka Kugi to find her father. Risuka speaks broken Japanese, as she is relatively new to the language.

Risuka's magic's Element is water, with its Type being time, and its Manifestation is Moment. She can essentially fast forward her life, changing her appearance and healing herself. If she wishes to, for a single minute, she can shed a sizeable amount of blood to take her prime form of a 27 year old woman where her magic casting and fighting are at peak condition.

The elementary schooler unlike any other, Kugi Kizutaka, is searching for "useful pawns" in order to achieve his own ambitions, comes to learn of Mizukura Risuka, a magician with the title "The Red Witch of Time." Risuka had left the Kingdom of Magic through the Gate, chasing after her father, a great mage called both "a God" and "a Demon." An unpredictable and unchained magical tale! 
 
(Source: Kodansha, translated) 
 
Note: The serialized chapters 16 and 17 were merged into one chapter in volume 5.

A series of crossover stories between characters from Monogatari and characters from Nisio's other works. Originally, 4 crossover short stories were released during the theatrical screenings of each Kizumonogatari movie. The stories were bundled up into Mazemonogatari, and included 3 unreleased stories. 
 
Includes 15 stories: 
Kyouko Balance 
Jun Build 
Nomi Rule 
Mayumi Red Eye 
Kuroneko Bed 
Risuka Blood 
Hitei Clear 
Iori Fugue 
Shiogi Ranger 
Akari Triple 
Rizumu Rock 'N' 
Mikoko Community 
Kuu Invisible 
Rai Roulette 
Magakoro Finisher

Nagasaki prefecture, in Japan, is a magical kingdom. While the wizards that live there are unable to cross the ocean, and are trapped in Kyushu, they still pose enough of a threat that Americans dropped the bomb on them during WWII. The residents are worried that this will happen again, especially if the regular humans decide magicians are a threat. 
Daughter of the most powerful wizard alive, Risuka Mizukura is ten years old, and living outside Nagasaki, searching for her father and killing evil wizards. Her blood contains spells that control time, and allow her to fast-forward her own life. Her ultimate technique kicks in only when she dies bloodily -- her blood will reform into herself at 27, at the height of her powers, for one minute. 
Her guide through the world of normal humans is Kugi Kizutaka, also aged ten. Kizutaka is a genius, and a sociopath. He believes the only way for people to be happy is to be ruled by him and views everyone he meets as a potential pawn, or slave. Including Risuka. 

(Source: easternstandard.pbworks.com)

What if Monogatari's Ararararagi, Zaregoto's Ii and Jun "Humanity's Strongest" Aikawa, and Okitegami Kyouko no Bibouroku's titular forgetful detective all attended school together? In 2002, NisiOisiN won a Mephisto Prize prize for his debut novel Zaregoto, Book 1: The Kubikiri Cycle. Part of the 15th anniversary celebration will be 4-panel crossover gag manga Seishun Kijin-den! 240 Gakuen (240 is a pronunciation pun - 240 can be read as "Nishio," so "Youth Oddball Story! Nisio Academy"). 
 
(Source: Crunchyroll)

Adaptation of the climax scene from chapter 1 of the first volume of the series done in commemoration of the release of the fourth volume.