Since Sandaime Hokage was able to suimmon Enma the monkey king and even monkey's do you think that his grandson Konohamaru will be able to summon Enma too. Since they were very close and most of the Hokage's where able to summon some kind of animal to help fight, look at The First with the Jinchūriki's, The Second unsure but most like a shark( just speculating, since it is said that he could summon water from anywhere even if there wasnt a body of water around), the THird had Enma, The Fourth had the Toads, the Fifth had the Toads and Kakashi next projected hokakge has his dogs and the the 7th hokage can summon the toads already; we all kno that Konohamaru and Naruto consider each other to be brothers and if anything was to happen to Naruto when he hokage it is more likely gonna be passed to Konohamaru who's gonna look after Naruto's child some what like Kakashi did for Minato the 4th Hokkage.
Since Konohamaru is gonna be the next hokkage its either he's gonna get enma or the toads as his summon. Do ya think the third may have left the scroll behind for his families usage, dnt say tht asuma didnt have a summon, we could speculate that he may have had it since summons are usually handed down through the family or student and teacher, give your thoughts? be kind its my first thread.