I haven't watched Duang Jai Nai Fai Nhao but based on the synopsis, they have a few similarities. Both male leads want to take revenge on their family. Both male leads are rich (in Hua Jai Sila, he became rich by his own means). Both female leads want to stop the male lead from taking revenge. Both male leads use woman as a means to getting closer to seeking revenge.

Similarities: Both male leads are harsh spoken. Both female leads have low self esteem.

Tags: #hardworking female lead, #love triangle, #adapted from a manga

Now, before I start, I do want to say that they are completely different stories. Saikou no Rikon focuses on the aftermath of a divorce and Chugakusei Nikki is about a teacher-student relationship over time.

The similarities I found with them is that they both made me so frustrated to the point I wanted to throw myself out a window. With both dramas, the love in the love triangle is so strong that you don't know who's going to get picked or what's going to happen. It leaves you with so much suspense.

They also both have characters (in my opinion) that you can't help but hate because they end up speaking the awful truth (Haraguchi Ritsu (CN) and Uehara Akari (SNR)). They are also technically "the other woman" so their presence may be irritating at times.

Similarities:
-Both have an older woman dating a younger man.
-Both have older man living next to/with older woman.
-Both have the woman feeling like she needs to get her life together.
-Both have an older man and older woman bickering (although the bickering in Last Cinderella is 100X worse)
-Both have a love triangle.

Differences:
- In Last Cinderella, the younger man seduces the older woman because someone told him to. While in DNWNKK, he asked her out because he was genuinely interested.
- In LC, the female lead is seen more as an old man while in DNWNKK, the female lead is feminine.