Death March kara Hajimaru Isekai Kyusoukyoku (WN) - 18-28. Boy in the Labyrinth City (1)

Collection of short stories.

- Description from Novelupdates

The MC (Minato) is a college student who died in a plane crash and was reincarnated in a fantasy world. He was raised alone in the wilderness by his succubus mother, and now he tries to make his way as an adventurer.

When Bai Xun was bored, she played a dating game recommended by a friend. She entered the game and must keep up the affection with seven different types of men as the only way to clear the game. Only when she gets seven hearts safely can she go home? After many deaths, Bai Xun knew it, and could only live by paying closer attention!!

- Description from Novelupdates

One moment, Luo Jing was at the brink of death after accidentally touching a power outlet while showering. The next, he was in the body of a man named Garen, with memories of a past he was never a part of flowing into his head. As he slowly gets used to the body of Garen, he begins to explore a planet beyond his own logical comprehension. His journey will see him go from surviving in a planet locked in the 20th century, to wielding secret techniques so powerful that they level cities overnight. However, his journey doesn’t end with Garen. Instead this is but the first of many bodies that Luo Jing will come to wield in his mystical journey between worlds.