[Miraluka]

Originally Posted by Forbin

The manga states that the author wrote the anime original stuff.

No, only the names of the unnamed characters who were involved with the LU and the unamed people like the sempai of Kuroko.

Spoiler for original stuff from the manga:

Graviton spoon-man, Light bender-man and Kuroko's sempai. No one of them had a name in the manga until the anime aired.

Spoiler for The original anime stuff from J.C.Staff::

-Saten and Uiharu meeting Mikoto in the beginning.
-Urban legends thing.
-Invisible girl.
-Tokiwadai Garden.
-Asphalt girl.
-"Computer parts".
-Random guys who were owned by Kuroko.
-Saten's power
... I can't remember anymore for now.