This is the similarities between both series:

1. Both have the same duration of 12 episodes and have sequel movies.
2. Have fights between gang-members and always strives to be NUMBER 1 of all the gangs.
3. Friendship, loyalty and honor has strong presence in both series.
4. The male-lead is the strongest!

The plots is almost the same while the story-lines are different. Both have self-absorbed and Hi-so heroines who bullies the heroes from the start. Both leads grow up in the same household, and both heroes are adopted by the heroines father. There is marriage-of-convenience in both dramas. A hate-love relationships also between the leads, and the hero secretly loving the heroine all the time.

Both have this paranormal genre, while the male-lead is an alien in "Star" the female-lead is a mermaid in "Legend", and both have super-powers as creatures. Both series follows up the path of true love through reincarnation, humor and excitement! And lastly, both dramas have Gianna Jun in role of the Female-Lead !