Gather and hold 700 stars at the same time in a game.
Ways to Complete
Stack Piggy Bank, Holy Night, Nice Jingle, basically anything that can give you bonus stars. It is recommended to play on a map with avoidable bases like Tomomo's Abyss, and the Miracle field effect for x2 bonus panels. Aru and Poppo are also very helpful with their hypers for this achievement.
As with many other achievements that require long matches, playing Star Breaker Episode 4 on Casual difficulty will confuse the AI into not going for Norma most of the time, allowing for one to accumulate stars quickly.
The requirements for this achievement were changed in Version 1.8.6. The change allowed for collecting 700 stars instead of 1000 stars, decreasing the requirements for players who had not previously completed them.