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  • The visual goals for Yuumi included creating a cute support due to having not done one in quite some time.[1]
  • A scrapped name for Bop 'n' Block Bop 'n' Block was Protecc/Attacc.[2]
  • Yuumi's in development name was Catbook.[3]
  • You and Me! You and Me! was a spell originally tested on Xayah OriginalSquare Xayah and Rakan OriginalSquare Rakan, when one of them died their spirit would attach to the other and would allow you to keep playing.[4]
  • Yuumi is voiced by Cassandra Lee Morris who also voices Nami OriginalSquare Nami.[5]
  • Yuumi's prototype model was a recolored Zoe CyberPopCircle Cyber Pop Zoe.[6]
  • Prowling Projectile Prowling Projectile's prototype particle was a cat from one of Lulu OriginalSquare Lulu's skins.[7]
  • Several scrapped spells tested on Yuumi include:[8][9]
    • A miniature version of Realm Warp Realm Warp.
    • A version of her ultimate that allowed her to attach to enemies and knock them back until they hit terrain.
    • A version of Prowling Projectile Prowling Projectile that would charge for a second and then fire at an incredibly fast speed.
    • A spell that would throw a boomerang like orb that would allow Yuumi to cast her spells from the projectile.


  • Yuumi is a magical cat familiar to a Yordle Enchantress named Norra.
  • Yuumi's name came from when she heard Norra say “you” and “me”, and thought that was her name.[10]
  • Book OriginalSquare The Book of Thresholds was originally written by a Yordle anthropologist in order to study how Yordle magic works and how Yordles traverse the spirit realm. It has been added over the years by generations of Yordle mages who explored the various gateways to and from Bandle City.[11]
  • The Book of Thresholds was given sentience by one of its previous owners in order to protect itself from those who would use its powers for evil.[12][13]
  • Yuumi and Book have been looking for Norra for around 4 years.[14]



Yuumi OriginalCircle Original Yuumi
  • Yuumi bears a striking resemblance, both appearance- and functionwise, to the Summon Aery rune Summon Aery Keystone rune.
  • Her splash art shows Yuumi inside Master Norra's house in Bandle City.
  • Yuumi's tail works as a rudder for steering book.[15]
Yuumi BattlePrincipalCircle Battle Principal Yuumi
Chromaskins Chromas: Citrine, Formal, Granite, Obsidian, Pearl, Rose Quartz, Ruby, Sapphire, Tanzanite
Yuumi HeartseekerCircle Heartseeker Yuumi
Chromaskins Chromas: Aquamarine, Catseye, Citrine, Granite, Pearl, Ruby, Tanzanite


  • Yuumi OriginalSquare Yuumi and Book OriginalSquare Book of Thresholds have become fast friends, united by their love for Norra.
  • It is stated on her Universe page that Yuumi OriginalSquare Yuumi (or Book OriginalSquare Book) has relations with Lulu OriginalSquare Lulu, Tristana OriginalSquare Tristana, and Teemo OriginalSquare Teemo, possibly during the time in Bandle City as Norra's familiar (or as a guide).
    • Book OriginalSquare Book (and possibly Yuumi OriginalSquare Yuumi) has observed Draven OriginalSquare Draven and Tamara during their return trip from Basilich to Noxus Prime. Lulu OriginalSquare Lulu and Tristana OriginalSquare Tristana were also observed fighting Noxians to a retreat. Book has no fondness towards Noxians and their violent tendencies.
  • During their travels, Yuumi and Book have encountered Braum OriginalSquare Braum. Yuumi rested on his shoulders for a time, protecting him from angry snow-spirits stirring up flurries in a hailstorm, while he brought her wriggling fish.
  • Yuumi and Book were attacked by Rek'Sai OriginalSquare Rek'Sai while they were investigating ruins in Shurima.


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