Kanji sticker. That it called teiso. Meaning that cornerstone. This is a stone to put in the beginning when you build a building. Japanese carve this kanji in the stone. In today, we use the cornerstone as a memorial.
This sticker, I want you to put on milestone of your life. For example, when you bought the electronic equipment. When you bought a refrigerator. Every time you see this sticker, will be able to recall that at the time.