The two was never ever seen interacting in canon besides being in Kaito's group for fighting Monokuma, and despite Rantaro being the first to die.
The two also has nothing in common as both are being the opposites. Despite never interacting, Rantaro is usually a carefree and relaxed person. While Maki isn't and is unfriendly to the others. When given the choice in the final trial, Maki offers to sacrifice herself to save the other survivors. The same choice is what led to Rantaro becoming the Ultimate Survivor, showing a similar willingness in the two to make difficult decisions for the good of others.
Both are also responsible "older sibling" types, with Rantaro being the oldest of thirteen siblings, and Maki taking care of younger children at the orphanage.
The ship is a rare pair compared to other ships, and is rivaled by others, such as Maki's most popular ship, Harukaito, and Amamatsu, Rantaro's most popular ship. People that ship them like their dynamic since Maki and Rantaro are the more cool-minded, mysterious characters with hidden talents. Maki is also seen to get annoyed very easily, most of the time by characters that are too hyperactive like Kokichi Oma or overly cheerful like Angie Yonaga. Rantaro is neither so Rantaro could bring out Maki's smile like how Kaito Momota, her canon crush, does just by saying nice things to her. Their color schemes (green/blue + red/black) blend together as well.