I'll make this very simple.. if you like ecchi comedy harem hijinks then it genuinely doesn't get much better than this manga. The balance of story, ecchi, harem, cute art and frequent laugh-out-loud comedy is just totally on-point. Don't be fooled by the torture element as it really serves as a great comedy-foil (without being over-used) to play off the character's antics.
Also don't be fooled by any overly pretentious reviews as this very much sits in the sweet spot between comedy, action, romance & drama that never takes itself too seriously but equally never becomes too episodic. There's plenty of cheeky mischief perfectly balanced with engaging story arcs and naughty 'accidents' that really make for an addictive read that's just hard to put down.
If you're familiar with Seitokai Yakuindomo and it's excellent comedy-timing then this delivers equally but with a much more consistent story, satisfying ending and character's you'll grow to love. Everyone has their penchant (and Ship) but personally I really rate the character art-work (Prez ftw!) and well-blaanced pacing where the story never felt too slow or fast.
As to the harem, well I won't spoil things too much but again if you enjoy harem shenanigans for what they are then this also delivers with sufficient 'progress' without overly spoiling the dynamic; which is some feat as a majority of harem-enjoyers will know.. precious few authors are able to successfully pull off that trick.
It's a real shame this isn't available in a licensed English version as it'd be a great addition to the collection. That said with a surprising number of original manga titles getting anime adaptations these days, just maybe we'll be blessed (or cursed in the event of a bad studio!) with this also being picked up. Fingers crossed!