Ena Costume 1 - Rapidly click the fake close button until a video of ENA and Moony dancing appears. This will grant you ENA Costume 1.

Fuchsia and Cyan - Zoom out until you see a grey rock at the far left of the screen. Click this rock, and the screen will shift into the drunk version of ENA. This will unlock the fuchsia and cyan colors.

Orange and Red - Go to the main page, and look for the words that say "OFFICIAL MERCHANDISE". Click the E, N, and A letters of the text. That will unlock orange and red.

Ena Diablada - Go to the Copyright 2021 at the bottom. Click the 0 and the 1 in this order.

This will grant you the Ena Diablada costume.

Grey and Pink - Rapidly click the fake close button until the dance video appears. Then, rapidly click the fake close button, then the fake minimize button until the easter egg says it's unlocked.

Green - Simply verify your email for this easter egg.

Spoilers!