The Ninja 2 (SCNJ-2000) does fit on a MSI P45 Neo (Description on MSI website). It is also sold under the name of " MSI P45 Neo-F ".
On those pictures it is mounted using the Universal Retention Kit (ie: with the backplate sold apart). I (hardly) managed to mount it without the spacer.
It is also working with the original pinpoint fixation but due to the weight of the cooler, the pinpoints tend to run away by themselves.
Memory slots 1 & 2 are overlapped by the fan: beware if you have a cooling system on your RAM, it may not fit anymore. (Click the pictures for bigger size)
