Yoon Jae Ho manga
Sung Hoon was a normal High School student, but one day he finds himself with a tiger that Hwangun didn't marry, and is told that the world will end if he doesn't marry that tiger. The story begins with the cute smile of the tiger girl.
Meet Min Woo. A normal 18 year-old high school boy. Well...normal except for being a total otaku. He does what every good little otaku boy does. He collects figurines and toys, wins prizes at cosplay contests and is a two-time champion of the fighting game "Metal Heart". Unfortunately for him, his social life is dominated by girls telling him to get lost, since his otaku-ness might be contagious. But after an accident while he is invited to participate in the playtesting of "Metal Heart 2", the main character to the game, Min Sia, materializes in front of his eyes at a cosplay festival. And now, Min Woo has to win Sia's heart in a real-life dating sim game with the fate of the world in the balance. Ok, so maybe not the world, but at least the fate of the company behind "Metal Heart 2" hanging in the balance. And who is this girl Nuri who appears following Sia, who claims to be Min Woo's childhood friend...
From Tokyopop: Nightmares are bad enough when asleep, but In Dream World, nightmares are real, physical monsters! Drake, Hanee, and Kyle fight these Nightmares with not only weapons, but "In Dream Cards". These cards have different elemental powers, and those who wield the cards are masters of their elements. Hanee and her friends must battle their way through the land of Nightmares to find their way home.
Eraser, the mysterious enemy that invaded Earth 13 years ago!! Before their overwhelming power, the entire Earth neared the verge of collapse. But at the last moment there suddenly appeared Earth's lone savior, The Beast: an ultimate weapon uniquely equipped to counter the Eraser's power!! The Beast is part of the MAGIC Brigade, whose commander-in-chief is also the founder of our Le Prince Academy... Ladies and gentlemen, I present to you, Mr. Vincent!