Why can't I switch pin decks?

In the Taiseido Bookstore at Scramble Crossing, I purchased a book (No. 54) which says you can switch between multiple pin decks:

Press the Touch Pad Button on the Pins menu to switch decks. Assemble a variety of pin sets, then swap between them to suit the occasion.

The Pins menu shows that I'm using Deck 1, but pressing the Touch Pad doesn't do anything. Is there something I need to do before I can switch between pin decks?

Solution 1:

Extra pin decks must be unlocked through the Social Network.

The earliest you can unlock a second pin deck is Week 2 Day 2 from Shuntaro Harima. You can find Shuntaro on Week 1 Day 7 on Center Street, but unlocking his ability requires the following social link chain:

Rindo → Nagi → Eiru (Week 2|Day 2) → Masaya (Cony X Cony) → Tsukihime (Cony X Cony) → Miss Banks (Week 2|Day 2) → Shuntaro Harima.