Commemorating... what?

Commemorating... what? is the fifth stage in Q1. What's in the Box? Quiz.
==Battleground==
*1 The Face spawns as the boss after 3.33 seconds100f.
*1 Hippoe spawns after 6.67 seconds200f.
*1 Metal Hippoe spawns after 13.33 seconds400f.
*1 Hippoe spawns after 26.67 seconds800f.
*1 Hippoe spawns after 30 seconds900f.
*1 Hippoe spawns after 36.67 seconds1,100f.
*1 Metal Hippoe spawns after 50 seconds1,500f.
*1 Metal Hippoe spawns after 53.33 seconds1,600f.
*Infinite Hippoes spawn after 66.67 seconds2,000f, delay 20~40 seconds600f~1,200f.
==Strategy==
A simple stage, use the Normal Cats to easily beat it. Giraffe Cat or any Critical Hit Cats can easily deal with the Metal Hippoes that appear throughout the stage.
==Reference==
*https://battlecats-db.com/stage/s01282-05.html
Category:Event Stages
Category:No Continue Stages