[m] As far as I remember, the story began with a couple. One of them drops something at drainage. The man tried to pick it up but there is something(looks like a frog`s eggs) inside the drainage. When the man touched it, it spread to his body and then controls him. He then infected his lover. The school of the mc of the story had gone on a field trip. He also likes a female classmate. She seems to include in a popular group. When they rode a cable car, a bird keep on hitting the glass of the cable car, which then cracked. The bird looks mutated. There is also a scene where his classmates that survived left him, but he saw his best friend. He got angry with the others, along with the girl he liked since they left him. Later, he found out that his best friend was the one who suggested the others to left the mc.

It’s a manhwa called One Day, Suddenly, Seoul is.
It has like 50 chapters out.