Recommendations

Both shows:
>> Are heavy on the romance.
>> Showcase a ML who falls in love with the FL quite quickly.
>> The Leads have a connection that's later found out.
>> The FLs used to be well-off but fall on hard times. In DJ the FL loses her fame due to a scandal. While in DDSSLLS the FL's father dies and she gets scammed out of her money.
>> The FL used to be renowned at the start of the drama. In DJ the FL was an actress, in DDSSLLS the FL was a pianist.
>> The ML comes from a wealthy family but he regards them almost as the enemy and keeps his distance.
>> The ML likes taking care of the FL. In DJ the ML sets an agency up for the FL; in DDSSLLS the ML sets the FL with her own piano academy.
>> There's a love triangle, but it gets dealt with quickly.
>> There's a secondary couple.

Both are psychological thrillers exploring someone else living inside you. Similar tone, storytelling and exceptional chemistry.

Both shows:
>> Shows an FL who relies on the ML at first.
>> The ML takes it upon himself to take care of the FL.
>> Both leads establish a strong friendship.
>> The ML falls in love with the FL first and pursues her.
>> The ML are loners before meeting the FLs. However, they both have an older man who they consider almost a fatherly/grandfatherly figure lend them a hand.
>> The ML ends up teaming up with a group of misfits.
>> BIOG has a darker plot than DDSSLLS.

Both are psychological thrillers exploring someone else living inside you.

Both are psychological thrillers exploring someone else living inside you.

Both shows:
>> Feature a kind of time travel. In Kairos, the ML is able to change his present by having the FL (who is one month in the past) change things. In 365, both the ML and FL travel back one year to change the outcome of their lives.
>> The ML is betrayed by someone close.
>> The ML and FL must work together to overcome a common thread.
>> The FL is actively engaged in the plot and knows how to overcome problems.
>> The leads establish a deep friendship.
>> The ML in 365 RTY has a group of friends he relies on; while the FL in Kairos has a similare net of support as well.

Heartwarming relationships.

Though one uses DID and the other brain surgery, the main theme of theirs is what is it like having someone else living inside you.

Both have to do with music, though the vibes are different the friends to lovers and the common passion is music is very common, in Do you like brahms? There is more of a musical accuracy for sure though, Symphonys romance is an Adaptation of Nodame Cantiable so it will obviously be for more lighter audience. : )

If you fell in love with the main girl and you want to see more of her works then watch either mountains and oceans if you haven't or watch closer to you if you haven't.

The main girl is in both drama.
They are both set in university/college but I don't want to be friends with you started in high school whereas mountains and oceans started in university/college.

They both time travel to make difference in the future. The main girl in i don't want to be friends with you is also the main in closer to you.
Both time travelling
The main girl is in both
Nice, cute romance

Both films take on about history and relatioship of Thai Buddhists and Muslims in the country. If you are interested at explore about this religious conflict, they would be interesting choices.

- both are set in parallel worlds (comics)
- both have characters who don't realise they are in a comic
- both female leads are quickly self-aware
- both revolve around romance and changing their fate

the storylines of both drama are quite different but similar at the same time. Both are about the rich & privileged people who used their privilege and power to step on other people. The characters in both dramas hide murder and their crimes together to save their elite status, also Bong Tae Kyu and Yoon Jung hoon are in both dramas as friends, accomplices or partners in crime. Even characters of Bong Tae Gyu(Lee Kyu Jin) in both dramas are similar(childish & stupid). Anyway both dramas has the same feeling and ambiance.

Fun Fact: As first Shin Sung Rok(ML in Return)was to play the main character of Joo Dan Tae which is later replaced by Um Ki Joon due to schedule conflicts.