JUMP FORCE

for this success you just have to go to the window of the improvements and modify either the j-skill or the capicities beyond level 1 (50 times)

Wouldn't stress too much about this early on though you could get this done early if you really felt like grinding tediously. Just play the game and visit the counter labeled "upgrade" every once in a while and get your favored j/ability skills to levels 3-5. As each skill grows, the cost of the upgrade in turn grows. Through natural progression, by the time your avatar hits level 70, you should have 10-20 ugrades via your preferred j-skills and ability skills.

To mop up the remaining 30-40, I highly recommend already having J-Skill Master achievement since this means you have 50 J skills and the mission "Upgrading 1" on Expert unlocked. J skill upgrade requirements from level 1-2 are by far the cheapest at only a singular stack of 8 green/red/blue energy. While the Expert Upgrading provides the best drops quantity-wise for skill energy. The amount of times you will need to complete the mission will vary due to the drop rates not being fixed but just keep at it and every 5 passes or so go to the upgrade counter and upgrade as many j skills as you can to level 2. Rinse and repeat till it pops

Note: you do not need to S rank mission. Drop rates vary vastly i.e. I've got nothing on an "A" pass and 2 stacks of 20 skill energy from a "C" pass