SINGAPORE - When South Korean actress Jung Yu-mi imagined her first action role, she thought it would be along the lines of the sword fights of wuxia film Crouching Tiger, Hidden Dragon (2000).

Instead, in the fantasy dramedy series The School Nurse Files, the 37-year-old is fighting jelly monsters with a BB gun and a tiny plastic sword.

"To be frank, it is not what I expected or dreamed of as a kid growing up," she says at a virtual press conference with regional media.

"But it was a completely new kind of action series which I got to experience."

While the battles were added later via computer graphics, she adds: "It was exciting and fun. Staff members would give me the 'okay' sign when I was done with a scene and I wouldn't be entirely sure what I had done. But still, I felt very satisfied."

The six-part Netflix original series premiered last week. It is based on the novel School Nurse Ahn Eun-young by South Korean writer Chung Se-rang, who also adapted her book for the screen.

The series stars Jung (Train To Busan, 2016) as the title character, who has the extraordinary ability to see monsters. South Korean actor Nam Joo-hyuk plays a teacher at the same high school, who discovers his ability to recharge Eun-young's powers during battles.

The 26-year-old actor, known for his roles in series like Weightlifting Fairy Kim Bok-joo (2016), says of his new role: "He is someone who doesn't know himself well initially. But when he realises that he can be the source of power for someone else, he changes and develops further."

On set, the two leads were each other's source of power.

Jung says of Nam: "He has a very quick wit and I think that influenced me and made me quicker in my reactions to him as an actress too."

But Nam is quick to demur: "It's the other way around. I feel like I was following her lead and that she really carried me on her back throughout the series."

Director Lee Kyoung-mi, 46, says in a separate video interview that she feels The School Nurse Files series brought out a surprising side to both Jung and Nam.

She says: "For Nam Joo-hyuk, it was like, how could someone be so lovable, so good-looking and so funny at the same time? And he very often brought more to the screen than just the directions that were in the screenplay.

"For Jung Yu-mi, it's how well she handled her action scenes. I had not known before how well she could manoeuvre her body to create action sequences."

The director adds: "On top of that, she incorporated a lot of fun, cartoonish gestures and expressions into her performance."

As for the other stars of the series - the numerous jelly monsters - Lee had a say in how they looked.

"There are both harmless jellies and those that Eun-young has to defeat. For the harmless ones, I wanted them to look cute - like animals in a nature documentary which are not that familiar to the general public," she explains.

"For the ones that Eun-young fights, I wanted to invoke fear and curiosity by drawing on phobias like trypophobia (fear of closely packed holes)."

Lee is relatively new to television as she is better known as a film director and screenwriter. Her debut feature Crush And Blush (2008), which won her best new director and best screenplay at the Blue Dragon Film Awards, was produced by South Korean auteur Park Chan-wook.

The strong female vibe of the project - with a female heroine and a female director and screenwriter behind the cameras - is familiar to Lee, whose works are often female-led.

She says: "The stories which are in talks to be created into films - most of them are about men and are male-centric, so I'll be way behind in the list of directors who get contacted. That's why I started writing my own films to direct, perhaps that's why my female characters are so angry."

She adds of the character of nurse Eun-young in this series: "I see the series as the personal growth of a heroine who develops when she goes through the process of wondering why she even exists in the first place."

Actress Jung agrees that beneath the offbeat fantasy exterior of the series is the beating heart of a complex female lead.

She says: "I feel empathy for her. She has to see these things which are unseen to others. I feel her loneliness. But she accepts her destiny and takes bold steps forwards."

The School Nurse Files is available on Netflix.