Have you noticed that the friendship guage in the stats screen is short, even when full? Once your character reaches the adult stage, you can start to earn TaMaToMo seals. Every time you earn a TaMaToMo seal, the length of the friendship gauge is extended (not just colored in, but some pixels are added to its overall length), which means it'll take that much longer before it runs down to empty. Generally, you'll earn one of the first three seals when you discover one of her favorite foods, favorite snacks, toy, clothing, and / or accessory. The fourth seal is earned by keeping your character for at least 48 hours after she becomes an adult. Once you've collected all four seals, your current character is added to your TaMaToMo Album (you can view the album through the book icon.) There are 32 characters in total that you can raise and collect. As the number of characters in your ablum grows, new travel destinations are unlocked. Some of these destinations unlock new icon backgrounds.