I thought I was hallucinating when I saw this game in the "latest updates" section: remember downloading it, what, like 4-5 years ago and it ended in stage 2 or 3? The girl didn't even have a voice, so when you clicked on her in the menu, you would only see the mouth moving (very cute animation however). And I still vividly remember the music for the 1st stage from back then. Have to admit though, no idea why they went for "bratty 10 year old younger sister" with voice direction - kinda destroys the vibe for me.
Anyway, one particular (very immature) review complained about difficulty, which might have been since readjusted, but still a few pointers: the game became a cakewalk when I figured them out. Even if the game is old, even if one of you finds it helpful, I'll be glad.
1) To run double tap A or D. If you press hit (Z) when running, you'll perform a short strike animation that will stagger every enemy in the game.
2) When anyone hits you, you become staggered - you can't move or hit, but you can press SPACE (emergency ability that launches you and everyone you hit into the air). In fact, when charging a group of enemies and you think that you'll be flanked/hit, just hold a finger on SPACE.
3) You have three different finishers for your standard hit combo. Holding UP will perform some kind of air punch which deals a lot of damage, holding DOWN will throw one of the enemies being hit behind you dropping everyone on the way. Holding nothing is fastest.
4) Forget potions: they don't scale with your health and every single coin should go towards stat points. MEN stat is also kinda pointless. I affects your overall MP pool and regen, but your gun ability (X button) consumes rather little. I guess upgrade it to 20-30 and forget about it.
5) You can hold X instead of tapping it and the girl will shoot continuously. The gun is essential in dealing with wasp enemies, since they retreat if hit in close quarters. You can even walk backwards and shoot!
6) The first boss is arguably the hardest. He can only be staggered by the second move of your combo and by sprint-strike I described in 1), but he will only attack, if there's some distance (his strike outranges yours), so either approach him from above/below or sprint-strike him. Annoyingly, some minor mobs in later stages seem to copy his abilities, so beware.
7) Some bosses will hit you when getting up from the ground (the succubus from the school and one of the later bosses).
Good game overall. Ideally would give it a 3, but since it's an adult game and considering the general quality of adult games, full 5 would probably be fair.