This is missable.
There are six capsule toy machines located throughout the game; two in Sakuragaoka (outside Abe Store), two in Dobuita (outside You Arcade), and two at the Harbour (inside the Harbour Lounge). This has to be 25 unique toys.
Capsule toys cost ¥100 each, so be mindful as Ryo begins the game with just ¥10,300 and receives ¥500 allowance per day until he begins working at the Harbour later in the game, where money is earned according to how well the player performs.
For me, this achievement unlocked after having more or less 35 different toys.