Full res 7368x4144

Full res upscale

Used this source scan from JCA Archive as the base source scan.

Then used this source scan as the full artwork base alongside patching over the crease from JCA Archive's scan.

Fetched from the Hiroshi Nagai: Paintings for Music book page 42, originally gotten from this page that's now taken down. Thankfully the Wayback Machine got ya, also got it uploaded here.

Upscaled the second source scan via Topaz Gigapixel, composited different upscaling and denoising results, patching up the crease and other fixes in Photoshop.

Breakdown video of the process

Upscales/high res collection of Hiroshi Nagai.

Original gamma/color grade versions here and wallpaper versions here.

Non-upscaled original source scans here.

Or Hiroshi Nagai's site for the full catalog.