Koichi sometimes has hallucinations while recording podcasts.
When you watch this video, you have to watch in a well-lit place, not too close to the screen, otherwise I heard you'll have hallucinations.
Fugu must have been hallucinating from the hallucinogenic mushrooms he ate.
You have memorized an illusion. You see it there, as if it's real, as if it's in your memory and brain. But it's not real. It's a hallucination.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.