What are the common themes in color comic hentai featuring big sister gangbang and lewd content?

hat? My lazy, coquettish and evil elder sister is not related to me by blood? What? She wants to be a big star. Luckily, I have an omnipotent system, so I can help her clear all obstacles! What? Mom and dad asked me to help her with her singleness. I'm still single! Why don't you care about me? System: I think you're a good match. I'll set you up. No, I refuse. I'm miserable to be her younger brother! I don't want to be my own brother-in-law!

The story of them happened in such an unexpected place, a mental hospital. To escape from the shadows of childhood, he thought he would hide for the rest of his life. But someone said to him, "I won't pull you out of the shadows, but if you want, I will stay with you in the darkness forever." 「Please note that the last 5 chapters can be unlocked by Coins Only at the request of our author. Thanks for your support~」

Buying a girl's first time with 2 million yuan? Giving her his gold credit card? Can the CEO really do whatever he wants in a cheesy romantic story? ! A real vice president of a company entered this virtual world and let’s see how he’s gonna teach the CEO from the two-dimensional world a lesson!

To survive in this world, one must be prudent, impassive, and merciless while he can't challenge someone out of his level nor consort with girls. Senior sister, he is just at Foundation Establishment Stage. Why would you bomb him with forbidden spells three times? Senior sister, it's just bruises. Why would you feed me with Immortal Pills? Senior sister, would you please stop pretending to be cute?

Li Nianfan transmigrated to an immortal cultivation world as a mortal. Knowing that he could never become a cultivator, he decided to live an ordinary life. But unbeknownst to him, his dog became a mighty Yaoguai king by watching him draw and write; the tree he planted in the backyard became the tree of the world by listening to tunes he played; a passerby he met, who gained enlightenment from the chitchat with him, became a Taoist sage and started a new era...

Like everyone else, Yun Caiwei found herself transmigrating into the past. Unfortunately for her, she was thrown into the shoes of a frail, delicate girl. Worse still, her male lead is a huge tiger! In his human form, the tiger flirts with her, pampers her, and possessively dominates her. In his tiger form, though, he becomes... an adorable kitty?