The combo read as this
5C > JA > JC > J2A > J2B > 5D.
Now what you want is the J2B to not come out after the J2A. In order for that to happen you need to do it close to the ground, so that instead of getting the dive you just land and instantly recover so you can do 5D. Practice it and then adjust the speed of your J2A > J2B.
Try it on Tager for starters, since it's pretty easy on him.
Let me know if it makes any sense, I'm bad at explaining shit but the basic idea is to do J2A Dive then as close to the ground as possible do J2B so that Arakune just lands on the ground and do 5D.