What’s Kirby doing on the Goodbye! BoxBoy! website?

Nintendo announced Goodbye! BoxBoy! yesterday, and opened a teaser site here. If you watch the little animation for just a short while, you’ll notice that Kirby appears. What’s up with that?

Kirby and BoxBoy! are made by the same developer. Is this just HAL Laboratory having some fun, or will Kirby be showing up in some fashion?

Thanks to Jake for the tip.