Silver Anniversary (結婚25周年, Kekkon 25 Shūnen) is the second stage in Silver Week.
After 3 seconds, Steel Snake will spawn, followed by 2 more. Mercury Sloth will appear with a boss shockwave after 20 seconds, with Steel Snake continuing to spawn throughout the battle, with their spawning speed getting slower through the battle.
Mercury Sloth has 2,400 HP and only takes 1 damage from non-Critical attacks, so make sure to bring at least one Critical Hitter, be it Moneko, Jurassic Cat, Space Cat or even Island Cat. Send out a wave of meatshields and Critical- Hitting units to deal with the enemies, they aren't that troublesome.
If you're later in the game, this stage can be rushed with Bullet Train Cat and Manic Lion Cat. Immediately spawn Bullet Train, then one Manic Lion Cat with a Starting Money Up (M) combo to complete the stage. This strategy can be used to farm lucky tickets.