“Mantis” Movie Review: Yim Si-Wan and Park Gyu-Young’s Netflix Assassin Spinoff Is Stylish but Messy

riya siddacharjee
8 minutes ago
3 min read

When Kill Boksoon dropped in 2023, it became Netflix’s unexpected flex in the assassin thriller game. Two years later, Netflix thought, “Why stop there?” and delivered Mantis. This time, the spotlight shifts to a younger, flashier generation of contract killers trying to rebuild their world after the fall of MK Entertainment and its top assassins.

Instead of a heart-wrenching mother and daughter story like Boksoon, we are thrown into a world of start-ups, rivalries, and plenty of knife fights. The story mainly follows four key players: Yim Si-wan, Park Gyu-young, Jo Woo-jin, and Choi Hyun-wook. Mantis comes back from vacation, finds his world is upside down, and soon realizes all are competing to become the number one assassin.

Mantis movie poster (Credits: IMDb) — *Mantis* movie poster (Credits: IMDb)

As the murder for hire empire crumbles, the film leans more on layered competition and shifting alliances than on a single assassin’s journey, even though the title might make you think otherwise. But here is the million-dollar question: Is the film actually worth your time? Will it keep you hooked on a Saturday night, or will you be checking your phone halfway through?

If you have not seen it yet, read on, but fair warning, we are diving into both the highs and lows of this Netflix spinoff. So buckle up, and let’s get into it.

Meet the New Gen of Killers

Meet Han-ul (played by Yim Si-wan), aka Mantis. He’s talented, cocky, and fresh off vacation when he finds out MK has gone up in flames. His solution? Launch his own killer company (because LinkedIn clearly wasn’t an option).

He’s joined by Jae-yi (played by Park Gyu-young), his childhood friend/rival, who’s been struggling to survive after being blacklisted from MK. Their chemistry is on point; sometimes they’re ride-or-die partners, sometimes it feels like they’d kill each other for the last dumpling.

Park Gyu-young and Yim Si-wan (Credits: IMDb)

Mentoring them is Dokgo (Jo Woo-jin), an older assassin coming out of retirement, plus a random investor (Choi Hyun-wook) who’s more obsessed with Jae-yi than is probably healthy.

The Good Stuff: Vibes & Violence

The real juice here is the Han-ul and Jae-yi dynamic. Their friendship, rivalry, and love-hate relationship give the movie its authenticity. Park Gyu-young especially kills it (pun intended). Her performance is layered with anger, ambition, and vulnerability. Honestly, she steals the spotlight from Si-wan more than once.

The review would be incomplete if I didn't mention Mantis; he is good at whatever he does. The action and the dialogue delivery were delivered on point.

The action? Pretty slick. It doesn’t hit the highs of Kill Boksoon, but it’s still sharp enough to keep you hooked. The final fight sequence, especially, is a banger. Plus, the whole “young assassins hustling for gigs in a collapsing industry” thing is unexpectedly relatable. (Freelancers, we see you.)

Yim Si-wan (left), Park Gyu-young (Credits: IMDb)

The Flop Side: Story Struggles

Here’s where Mantis stumbles. While Kill Boksoon had laser focus on one woman, one moral crisis, this spinoff tries to juggle too many ideas. Assassin unemployment rates? Shaky company politics? Side plots that go nowhere? It gets messy.

Si-wan's Mantis, despite being the title character, doesn’t feel fully out. For most of the movie, he’s just orbiting around Jae-yi’s goals. Noble, sure, but a little hollow. Honestly, Jae-yi should’ve been the main lead. Lee Tae-sung’s direction is solid, and the film starts with the right hook, but it slips away into a half-baked plot. Too much information ends up spoiling the broth.

Final Verdict: Should You Stream It?

Mantis is like that scrappy younger sibling trying to live up to an older sister’s legacy. It’s fun, flashy, and occasionally heartfelt, but it doesn’t quite cut as deep as Kill Boksoon. If you’re here for slick fight scenes and killer chemistry between Si-wan and Gyu-young, you’ll have a good time. If you wanted the same emotional depth and tight storytelling as Boksoon? You might leave a little disappointed.