Totally obsessed with the creepy-cool vibe of Leon’s place—his house is basically a character in its own right in 'Shinbi Apartment', and I keep going back to the arc that revolves around it. The core episodes that center on Leon’s house are the three-part arc titled 'Leon's Arrival', 'Midnight at Leon's', and 'Leon's Secret' (you'll find these grouped in the middle of Season 2). Those three episodes dig into the mansion’s traps, its mirror rooms, and the way Leon uses the house to test Hari and Doori, so they showcase the location front and center.
If you want cameo-heavy or later callbacks, check out 'Return to Leon’s Mansion' in Season 3 and the special OVA 'Leon's Last Night', which ties up some of the house’s mysteries. The art direction really leans into gothic atmosphere across all of them, and the soundtrack shifts when the crew enters the house—one of my favorite audio cues. I love how the house evolves across these episodes; it’s not just spooky scenery, it grows more sentient, and that made me root for the characters even more.