[GE] Add 1 character from a different anime to another anime

So I was going around the forums earlier and I noticed a picture and quote from a user, more specifically pyonPyonWarp-kun. His avatar of Gasai Yuno and his/her name and quote from To-Love RU made me think, "what would To-Love RU have been like if Yuno were in it?"

Now, to simplify the thread:
1. Choose an anime
2. Choose a character from a different anime
3. Include new character into first anime
4. Modify ONE attribute about the said character
5. Post why.

Now, I'd modify Yuno's Yandere level. She'd still be a crazy-ass Yandere, but not to the point of her in the anime killing everyone. She would certainly be more violent than the Tsuns in To-Love RU. Also, TLR doens't really have any Yandere anyways. It's a needed element in TLR.

Yuno kills everyone except Rito. Yuno vs Yami would be worth watching.

Choose an anime
Lucky Star

Choose a character from a different anime
Toshino Kyouko - Yuru Yuri

Modify ONE attribute about the said character
Make Kyouko high school age.

Why?
Kyouko is way younger than the main cast in Lucky Star. As for the selection of character and series, I can see Kyouko and Konata getting along.

Choose a Visual Novel (cuz I hate the anime)
Fate/Stay Night

Choose a character from a different visual novel (cuz the anime is 'nonexistent')
Ryougi Shiki - Kara no Kyokai

Modify ONE attribute
Shiki becomes Assassin class Servant

Why?
Anyone who has Shiki as his Servant would be undefeatable. Saber's Excalibur? Cut it down. Berserker's God Hand? Cut it down? Holy Grail itself? Cut it down.