YLAB is a South Korean production company which has produced numerous manhwa and manga series. The Super String Universe is their flagship shared universe which multiple of their series are set in.
Blue String is their second shared universe, centering on youth action stories which are set in neighbouring cities in the Gyeonggi province. There's also a Red String universe, focused on romance stories.
The order follows YLAB's official website timeline (which is apparently a bit out of date).
Suggested reading orders (aside from release date or chronologically):
https://superstringuniverse.fandom.com/wiki/User_blog:Solideodoxa/Reading_Order_Suggestion
https://www.reddit.com/r/DistantSky/comments/kt250y/super_string_theory_ylab/
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