How to get Character Pixels in NTE? Pixel art collectibles guide

Character Pixels are a collectible system in NTE. Each character has a pixel-art portrait/illustration obtainable through: 1) Reaching specific affinity levels with characters; 2) Completing character Day Off events; 3) Random drops from gachapon machines; 4) Specific events and achievement rewards. Collecting Character Pixels unlocks a display cabinet feature in your personal housing. Some rare pixels have collection milestones with bonus rewards.