Other than making dreads whatever the usual way is (I don't have or make them myself) there are other ways to make more stylized dreads. I'd look up some Lucio wigs from Overwatch; more than one person has used foam for his pool-noodle-sized dreads. There's plenty of awesome-looking foam wigs
out there that may inspire you. There's also this
tutorial which kind of merges the two methods.
I feel like I've seen this hairstyle on another anime character before (or maybe a Danganronpa one?) but can't remember who it was. I'd definitely research other characters with similar styles though since you'd be more likely to find a tutorial for an older character than a newer one.