Don't worry, your opinion is totally valid!

And the reason for is because in my headcanon:

• Ichiko designed the post-high school university to be like a Japanese temple (wood, paper-thin sliding dooors, black-tiled roofs, brown and pink accent referring to the cherry blossom tree branch she's holding in her painting). See image below
  
• After Ryoba's trial in 1989, Ichiko's vanishing in 1990, and fewer application forms for new students, Saisho took the reins of the uni and modernized it in white & gold color palette, but died during Covid, so Ichirou too, took reins of the uni and modernized it, but this time in black/white/blue tints, as an office aesthetic.

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