no 1 dou zhao defender

Spoilers!! (kinda)
Story-wise these dramas aren't that similar, but Endless Sea reminds of Twelve Letters. The idea of two young people trying to change their parents' / grandparents' fate with a letter as the key seems similar. While Endless Sea is about a time loop where both leads end up on the same day several times, trying to break the loop; Twelve Letters features the characters from the present trying to connect to the leads from the past via a letterbox.
Twelve Letters is much more complex and heart-wrenching, and Endless Sea is a quick, easy watch.

In the 1990s, Chen Yi and Miao Jing became acquainted because of their parents' acquaintance. At first, Chen Yi is hostile to Miao Jing, until after an injury, Miao Jing's kindness begins to change the relationship between the two. However, the good times did not last long. Chen's father died, and Miao's mother disappeared. The two adults did not get together, but the two children had to depend on each other. When he came to college, Miao Jing bravely confessed, but Chen Yi was involved in the arson case and became a key witness. To protect Miao Jing, he forces her to leave Tengcheng and cooperate with the police to arrest the suspect.

Many years later, Chen Yi ran a billiard hall, and Miao Jing returned to Tengcheng to audit Good Luck Logistics. The two met again.

Spoilers!!
- Xianxia/Xuanhuan, Romance
- In both dramas, the main leads seem to have a past connection like a fight/separation which the FL doesn't remember (+ both FLs killing their MLs on their wedding day °o°)
- FLs seem ordinary at first, but do actually have powers

Similarities:
- The Palace Gambit feels like a short Ming Dynasty version of Story of Yanxi Palace
- Both FLs navigate their way through the palace scheming to avenge their sisters
- Stories progress similarly
- Similar characters, like Lu Jiuning & Wei Yingluo;
Noble Consort Xian & Empress Fuca;
Consort Chun & Noble Consort Gao;
Prince Ning & Fuca Fuheng
Yunxiang & Mingyu ...

Differences in The Palace Gambit:
- Mini Drama, hence the fast time skips
- FL was a bit rash and hot-headed sometimes and her actions were much more unrealistic than FL in SoYP

Similar vibes, but we'll have to wait for these to be released to actually know
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Everyone at Yangming Middle School knew that Zhou Wan was introverted and silent, while Lu Xi Xiao was unruly. The two couldn't be more different. No one expected that one day, these two would stand together.

What you can watch while waiting for "Never-Ending Summer":
"Lighter & Princess"!

Similarities:
- The typical "good girl x bad boy" trope, lol
- Break-up arc
- In both dramas, FL and ML have rather complicated relations with their families

Differences:
- Reversed familial circumstances of FL and ML in both of the dramas (L&P: FL's family is well of, while ML's isn't vs NES: opposite)

(My thoughts are only based on the novel)

Similarities:
- Family-centered dramas
- Light-hearted comedy, maybe...
- Li Yunrui (ML in Yummy 3x) also plays the father of the 5 sisters in Perfect Match (he only appears in one episode though)

Differences:
- Perfect Match: multileads drama
- Yummy Yummy Yummy: Isekai / Time Travel

Similarities:
- Historical fiction and romance
- Both FLs disguise themselves as men to enter the military
- Setting: academy/training camps
- Both are strong female leads who are skilled and stand out amongst the others
- Brotherhood: FLs bond with male comrades, friendship and loyalty as central themes

Differences:
- FLs have different goals (LotFG: revenge vs. AMA: investigation of her brother's death)
- Time period (LotFG: Northern Wei dynasty vs. AMA: Republican era)