I notice you're asking for a blog post related to the terms and “indo18.”
To clarify:
This likely refers to and #18 (a hashtag or date, e.g., July 18). Possible meanings:
The 18th couple to enter the show is particularly interesting. Min-ji (22) and Joon-oh (24) have been dating for a year and are known for their cute and playful dynamic. Min-ji is a bubbly and outgoing college student, while Joon-oh is a calm and collected graduate student.