Lore drop:

My sona (Mamoru) in the alternative universe who's an engineer. The photo was taken by Hellen (his ex in every universe) in 1985 while Mamoru used a slide rule for the last time after his company bought calculators for every engineer. She gave him this picture with "memorise" text, to remind him that they had a great time together. However, shortly after, their relationship ended due to their misunderstanding. Mamoru rediscovered this picture at the age of 60 and tried everything to find information related to their relationship, but most of it disappeared after they broke up. He even couldn't remember any of her contacts. He really wanted to see her again and apologize for everything, he couldn't forget her.