Menma is the son of Kushina Uzumaki and Minato Namikaze in the alternative universe of Konoha. Making him Naruto Uzumaki of that world, he is the Jinchuuriki of the Nine-Tails Beast, Kurama. He has spiky black hair similar to that of the Naruto we know. He also has a Sharingan on his right eye. He’s abilities are very similar to that of Naruto.
If you’d like to know more about the movie and it’s spoilers click here: Naruto: Road To Ninja [SPOILERS].
I’d like to thank amandas-sketches for drawing such a wonderful image of Menma and Kurama. You should definitely go and check out her work!