I absolutely hate it. I don't mind teen crush concepts in general but it doesn't suit Kep1er. At all. The members (except maybe Dayeon) all suit other concepts better (elegant, hiphop, girl crush, cute). None of them are shining in the teen crush concept or their debut. Plus they're honestly too old. Teen crush implies that they're teenagers but four out of nine members will be adults this year. Yujin is already 25. Xiaoting and Mashiro are 22. Chaehyun will be turning 20 in 3 months. Compare that to Weki Meki who invented the teen crush concept and Itzy who is the most popular group with it. Weki Meki's members were 14-20 years old when they debuted with an average age of 16.8. Itzy were 15-18 and their average age was 17. In comparison Kep1er's age interval is 16-25 and their average age is 19.2 years old. Significantly older. And the fact that Chaehyun and Xiaoting are the main centers of the group doesn't make anything better. I don't know who the genius was that thought it was a good idea to debut a group with two adult centers with a teen crush concept. Like come on. Pick something that actually suits them.
The whole execution also looks messy, half assed and cheap. It's like they had zero budget and the whole debut is just poorly put together.
I don't know if it's too niche but I think they would have slayed a nightmare/horror concept. Similar to Dreamcatcher put softer and more upbeat. Like Dreamcatcher, Izone and Loona mixed together. The members good at elegant concepts (Xiaoting, Yeseo, Chaehyun, Yujin, Hiyyih) would pull it off perfectly and the members more suited for girl crush (Hikaru, Youngeun, Dayeon) would still have opportunity to go hard. Mashiro I'm a little unsure about but she did a good job in both Fiesta and MITM so she should be fine (plus imagine her gaze in a horror concept. she would be terrifying). It's age neutral (neither Yujin or Yeseo would look weird performing it) and Chaehyun and Xiaoting both suit the concept and would bring the group together.
Xiaoting would be so powerful I'm dead just thinking about it.