This comparison may be a stretch in that it’s more broad, but while I was watching EF I thought it had the same vibe as this drama. These are both dramas with very sweet moments that’ll have you grinning, giggling, and kicking your feet. EF and NBY both incorporate a taboo/forbidden romance and both I would say have light drama. NBY is taboo in that it’s boss/employee and younger man/older woman. However, they are different in that the characters in NBY are in a sports drama and the characters are older.
Here’s the plot summary: Liang You An, an executive assistant to a powerful boss has been stagnant in her position that was going nowhere. With plans to resign, she got her opportunity by meeting Song San Chuan, a professional badminton player going through a traumatic period in his life which rendered him stuck. Their chance encounter sent both on life and career altering paths that had them first becoming acquaintances, then friends, and then slowly growing into something more. While she encouraged him to be the first person ever to transfer from professional Badminton to professional Tennis, he at nearly 10 years her junior provided support and uncharacteristic wisdom. Could these two seemingly different people ultimately succeed in their goals, life, and love?

I also recommended the Chinese remake of this k-drama which is called “Love The Way You Are” (2022). If you want the same vibe of forbidden/taboo couple and non-blood related sibling-like relationship, SITR is a good option. However, SITR is way more heavy in terms of the drama/melodrama, does not have as much of an innocent feel since the characters are older/more mature, and there is way more parent opposition which is a huge part of the plot. SITR and LTWYA are also both noona romances.

Here’s the plot summary: Yoon Jin Ah is a woman in her mid-30s who doesn’t know yet what it’s like to date a man. She’s been dumped by a man many times because of her clumsy, reckless, and foolish behavior. And again, a man she wanted to marry dumps her for the worst reason ever: that she’s like bland, tasteless devil's-tongue jelly, which means she’s not attractive at all as a woman. Just then, Joon Hee appears before her with a broad smile on his face. He’s as refreshing as a soft drink. Joon Hee is Jin Ah’s childhood friend's younger brother, who used to live next door. Jin Ah has always remembered him as a little kid, but one day, he comes back as a really masculine man. When she is surprised by his change, her gut feeling tells her that she would truly fall in love this time.

The sweet love story of Yin Yi Ke and her childhood partner Xu Guang Xi. Seemingly having a perfect life, Yin Yi Ke has lived her 32-years-old life as a matter of course. Whether in the company or at home, she is thoughtful all around. Like a never-tired Wonder Woman, she takes care of everyone around her except herself. Everything changes, when she meets Xu Guang Xi, the young man who used to often visit her place for meals during their youth. Returning from his studies abroad, Xu Guang Xi, the boy who used to just feel a sense of dependence on Yi Ke, is now attracted to her. But chasing Yi Ke is nothing short of a difficult feat. It entails a fast-moving life and ultra-realistic pressure. For love, Guang Xi tries to become more mature and adjusts his footsteps, taking firm steps toward Yi Ke. The two throbbing hearts, who have experienced countless challenges and choices, start getting closer little by little. Understanding that the best love is not to sacrifice each other, they attract and respect each other so that they can both become better people.

Similarities: non-blood related sibling-esque relationship, light drama/not too heavy, forbidden romance
Differences: older woman/younger man, older characters