The Battle in Journey to the West - Chapter 17 - 0: Wukong Encounters Wusheng in the North Sea

An unnamed 34-year-old Japanese NEET is evicted from his home following his parents' death.

Upon some self-introspection, he concludes that his life was ultimately pointless.

Walking down a street he intercepts a speeding truck heading towards a group of teenagers, in an attempt to do something meaningful for once in his life he manages to pull one of them out of harm's way before getting himself in the way of the truck and dying.

Awakening in a baby's body, he realizes he has been reincarnated in a world of sword and sorcery.

He resolves to become successful in his new life, discarding his past identity for his new life as Rudeus Greyrat.

Liola—the best assassin in his world—has vowed to kill no more. He was being chased by an assassination organization when he accidentally dropped into a parallel universe: through a dimensional gate and into poor teenager Kaiser’s apartment. Instead of going to the government shelter for lost dimensional travelers, Liola and Kaiser wind up going to school together.

Liola has been trying his best to live the life of an ordinary person, but after certain things happen one after the other, he begins to realize that being an ordinary person could be harder than being an assassin.

A free spirit meets her match in all-around perfect bachelor whose humorlessness is his only flaw. When Xia Zhen reaches the unfortunate marriageable age, she is forced to go on a blind date where she meets Pei Cheng An. Her cunning plan is to pretend to be completely infatuated with her date in front of her mother, while sabotaging the actual relationship. Except Pei Cheng An isn’t the type to follow the script.

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In Xia Zhen’s opinion, Pei Cheng An is a person whose way of thinking belongs in the last century and whose manner of speaking reminds her of her grandpa. But since he looks dreamy and has qualifications, she’ll just pretend that she has fallen for him at first sight.

Eh? Pei Cheng An also finds her good enough to start a relationship with.

Great. Now when he finds out that she’s not a suitable partner for marriage and dumps her, she can return home all heartbroken and request to temporarily go on a brief no-blind-dates period. This is excellent. However…

“I’m so unreasonable. Why aren’t you breaking up with me?”

“A man should be tolerant towards his girlfriend.”

“I’m so mean to you. Why are you being so kind to me?”

“Girlfriends are meant to be spoiled.”

“I’m not gentle or considerate. Why aren’t you breaking up with me?”

“Likely it’s because… I like you.”

- Description from Novelupdates

He—an enigmatic and cold-blooded soldier with a mysterious background.
She—a ruthless and bloodthirsty spy.