kpop1-5, Exercise 1: Showcase, concept, comeback

Model answer:

Debut showcase: how many agencies present a new group to an audience, using online marketing and television broadcast promotions rather than radio.
Concept: the type of visual and musical theme an idol group uses during its debut or comeback; it can change between releases and may be a general concept or a theme concept (such as cute or fantasy). New groups often debut with a concept already familiar to the market.
Comeback: a promotional cycle for a new single or release, "even when the musician or group in question did not go on hiatus".
The English word misleads because it suggests a return after a break, whereas it only means a new release cycle.

Source: Wikipedia, K-pop (Marketing).