What are the key features of hentai mutual penetration manga?

Erlang Shen! Why did I wake up with the Red Cord fastened to your hand and mine?! Did Yue Lao fail in his job?

Several women who once got into trouble because of money formed an alliance. They seek after rich men, have an extravagant life, and believe only wealth can bring power to people. Although they are crazy about money, they will finally understand money isn't the only important thing after experiencing love, disloyal friendship and life risks.

QIAN BUDUO IS A LOSER, PENNY PINCHER AND COLLEGE BOY WHO HASN’T GOT A PENNY TO HIS NAME. BUT ONE DAY HE UNEXPECTEDLY GETS HIS HANDS ON THE DEEP POCKETS SYSTEM THAT OFFERS HIM MONEY MORE THAN HE COULD SPEND. HOWEVER, THE MONEY IS ONLY FOR THE COMPLETION OF ALL SORTS OF WEIRD TASKS ASSIGNED BY THE SYSTEM. A COMPLETED TASK WILL KEEP HIM OUT OF HARM’S WAY OR WIN HIM SPECIAL BONUSES WHILE A FAILED ONE WILL PUT HIM THROUGH HELL! FOR A STINGY GUY LIKE HIM, SPENDING MONEY LIKE WATER FOR THE COMPLETION OF TASKS IS DRIVING HIM NUTS! AND THERE’S SUPPOSED TO BE A HIDDEN SECRET BEHIND THIS SYSTEM AND UNDERNEATH ALL THOSE RANDOMLY ASSIGNED TASKS...

Born in a stone, I was treated as a little monster. When I‘ve grown up, I fulfilled my master’s wish – to marry into my wife’s family. From then on, I got a nickname “kept man”. However, nobody knows that I am the most extraordinary swordsman in the world. I don’t care whether they call me monster or Zhui Xu(son-in-law living in the home of his wife’s parents). Just wait and see how I conquer the world!

A young boy walks away from home after a quarrel with his father at night and later gets kidnapped. He finds himself in a strange laboratory after waking up, facing a challenge…

Talented Enginer Han Yushan picks up a young master, Cheng Yifan out of the blue. As he watches the young lady he spends time with everyday morphing into a superstar at the workplace, Cheng Yifan can't help but think, "She's such a great person. Wouldn't it be a shame if I let someone else have her?" It's a first come, first served basis. Living together is how sparks fly!