They both have high school young men, and all the members learning a sport, the only difference is that water boys didn't have delinquents. Rookies were a bunch of bullies, thugs, outcast brought together to play baseball.

They have a similar concept of young boys competing in a sport, water boys synchronized swimming and tumbling with rhythmic gymnastics. It was during high school, through the sport they learn to build their friendship and love the sport.

The movie and series speak such deep volumes.
Both are based on a classic song- first love and Ito.
Both are stories based on first love.
They both are a love story and fates bring the leads to meet each other again later in life, sparkling a second chance at love.

I recommend all the series for Falling in love like a romantic drama. They both are realty tv shows that cast actors, actresses and models to showcase a story. Each episode has a romantic plot they act out. The difference is with “ when we write love story” it is with the same couple and their storyline builds on each episode. “Falling in love like a romantic drama” the cast or the scriptwriter decide who gets paired. Each storyline for their “drama” is super cute.

The first series I thought of was Ming Lan while watching Love like the Galaxy. Both female leads are clever and scheming as a young child. They do this to survive the household they live in. Both husband/fiancee are military generals who adore and loves their wives.

Both have ML as the military general who loves and adores FL.

FL is an intelligent lady and learns to fall in love with ML even though he wasn't her first choice.
Lots of palace politics and romance.

Both leads have fantastic chemistry!

When I first saw Tomorrow, it just had this odd sense of similarity to IOKTNBO.
First off, the female leads are headstrong. The supporting cast is just a fantastic group! I love each and everyone one of the character and the stories they had. Both had a theme closely related to suicide, mental health, and healing from these scars.

This is the only series I can think of when I think of cute and fluff romance. I personally prefer Her Private Life since the chemistry was just more to my taste. Beauty Inside was still cute but I think it was more because ML played this odd cold character that it was really hard for me to love it.

Both are reality tv shows in Japan. They both have wholesome content and couples that I enjoyed watching.

So much went on in both series, all the side characters and how it went so well with the storyline remind me so much of how similar this series is. Although if you're looking for a bit more of a romance, I think LST has it. SSS is about the ML

The first thing that came to mind was Chinese Paladin as I was watching Sword Snow Stride. These were the closest similarities I can find:

Lots of traveling
A bit of a love line going on
Wuxia

Because of the wholesome love story between the leads, they remind me of each other. Koi Desu is just a bit more exciting and funnier and Forever Love had a bit more typical Asian drama and conflicts to overcome.