Notebook

With this icon you'll be able to see your Tamagotchi's friends, and the Tamagotchis you've raised before.

These are the three options you can choose:

ともだち [Friends]
ファミリー [Family]
おはか [Grave]

Friend list

Here you can see all the Tamagotchis you've connected to.
Press Ⓐ to see the next friend or Ⓑ to see more info on the current friend.
The first time you press Ⓑ you'll see the friend's gender ("おす" if they're male, "めす" if they're female), and the second time you'll see their friendship level.
If you press Ⓑ a third time you'll see their name again, but, if you press Ⓐ while the gender or friendship level is shown, you'll be asked if you want to delete that friend from the list…
Choose the first option (はい) to do it or the second one (いいえ) to go back.

[Read the connection section for more info on the friendship levels.]

You can keep up to 50 friends in the list!

Family

Here you'll see the Tamagotchis you raised on previous generations.
Press Ⓐ to see the next one. You can see up to three generations back and their partners.

Grave

Here you'll be able to see the Tamagotchis you've lost…
Press Ⓐ to see the next one or Ⓑ to get more info on the current one.
You'll be able to see their age, weight and cause of death.
There are three causes:

たまごっちカゼ [Sickness]: Your Tamagotchi spent 12 hours sick or got sick five times during the same stage.
えいようぶそく [Undernutrition]: Your Tamagotchi spent 12 hours with 0 Hungry hearts.
じゅみょう [Old age]: Your Tamagotchi got many care mistakes during the senior stage.