sounds like the test went pretty well which is good to hear.
Not sure how to describe nippon ichi games other than a sort of time sink where the player can get huge numbers, max level is 9,999 and stat caps are generally 99,999,999 with huge top end damage numbers if you decide to take the time to set it up.
Thing is, a single character can hit level 9,999 many times over by reincarnating as a level 1 and getting bonus stats based off of their prior level, max reincarnation level is 186,000 based off of what guides are saying, so a character will go from 1 to 9999 about 19 times for maxed out bonus points to add to his or her stats.
Disgaea itself has a few extra things to add on to that that can get in to pretty major detail as well, there's the item world, a 30, 60, or 100 floor dungeon depending on the rank of the item, normal has 30, rare has 60, and legendary has 100. Killing a boss every 10 floors boosts the items stats. Most items have something called residents which can be killed and subdued, boosting their level and allowing them to be transferred to other items. There are guides on optimization that go into pretty heavy detail about it.
Later versions of disgaea have a thing called class world, it's basically a 10 floor dungeon like item world but for characters. Every incarnation of a character gets a certain number of class world runs based off of the rank of their incarnation (good for nothing, bad, normal, good, very good, and genius. Can't remember the in between ranks off hand, generally only want to go with genius if possible.) Anyway, the importance of class world runs from a non-exploiting perspective is that the run will raise the characters aptitude up to ~125% for story based or dlc characters. Aptitudes are raised if you kill the last floor boss or a special enemy called drop outs which are exact clones of the character you're doing the class world run for.
For example, Adell in my disgaea 3 game tends to do about 3.1 bil or so with his strongest single target skill on average, 800 mil on the low end mainly due to it being fire based and having enemy resist get in the way. If I decided to put an enemy to sleep and break their fire resist, along with having him equipped with an ability that does 100% more damage to sleeping enemies, that can raise to about 13 bil with him completely buffed. If you search disgaea videos on youtube, there are some showing damage up in the high trillions. XD