When you are in the E-Church Depths (I did this in Aurica's path), there is a chance you'll fight some Temple Guards, these guys have a tendency to heal themselves when their HP is low, first, start singing Boom at the beginning of the battle and complete one harmonics gauge, use skills to keep your bar filled high and keep them healing, when Boom has been charged all the way to 2000 (shouldn't take more than two turns), use it, that way, the new level of harmonics will become available, do the same now, too and again later until you have all three harmonics gauges filled, if you used skills all the time there should be only the back row enemy left, make sure not to kill this guy but hurt him as much as you can (his HP bar should be yellow, more than that may not do it). If his HP are low, he'll use a healing spell every round that heals 1500-2000 HP, start singing boom once more (with max MP), make sure you find a way to keep his HP low, skills, simple attacks, whatever you prefer, wait with some characters if you can't do anything else. Do that every round until Aurica's MP runs out and the spell is casted automatically or she has around 20 MP remaining (if you use an MP recovery item the results will be twice as good).
I got 2117 DP using this strategy for the first time, Aurica had 2691 MP using the Bubble Passion costume and no MP recovering item used, Aurica was level 51, equipped with Warm Sweater and Barrier Ring that had Mp boosting and Defense boosting Enchantments. This process takes about 6-7 minutes, maybe more, and is requires minimum effort to pull off.
After completeing the game, save your file when you're prompted to. The game will reset on its own. When you go to the Title Screen, a new option will appear: the Extra Menu. In it, you can view the Photogallery, listen to the music in the game, and other things.
Once her airship is finished and you can go above the blastline for the second time, go through the dragon heart into the village. There Kruche will be given a toolbox by the owner of the shop behind the tree. While experiencing this event you will be allowed to buy things from the shop where you can buy rare grathmelding cards for creating a tower and others. You will also get to know more about Krusche as well! Watch the event for yourself!
All of the girls have 10 levels in their cosmosphere, but Lady Shurelia only has five (it's not a real cosmosphere anyway) and a limited amount of song magic. Although most of hit has the same effects only combined. So Lady Shurelia's power comes from how many times she can use the song. When you complete her cosmosphere go too the song shop and buy as many as you can!