Hitachi Ao Gami blue paper steel is white paper steel with added alloying elements which improve its toughness and wear resistance. In practice this means you can leave blue a little bit harder than white and get the same toughness. Once hardened and tempered both types will take and hold a fine edge with no persistent burr.
To maintain the purity of the steel and minimise carbon diffusion use a charcoal forge if possible. Forge at 800-900 Celsius, forge weld at 1100 Celsius using borax to flux the surfaces. After forging and grinding, cycle at 770 Celsius to release any tension from the forging process, harden at 800 Celsius and quench in oil, and temper at 190 Celsius.
530mm x 30mm x 4.5mm Unhardened Billet