An Angel´s Melancholy
Hot Spring Tales
I want to know what are these stories about,but with no SPOILER PLEASE

They give a little bit more info on some of the characters. (possible spoilers)
There are a few cutscene's that you need if you want to get the complete gallery for Eushully's Room.
Also allows the Version 2.0 Bonus Characters when starting a new NG+.

The characters you get in each map and their level/skills are fixed.
Make sure you complete the levels with all clear conditions.

The stories themselves didn't seem like the normal route type of quests with a story progression.
Just a few quests loosely tied together by some cutscenes.

"An Angel's Melancholy" its a side story about the 2 angels. So, if you completed all the events involving those 2 in the main storyline you will have no spoilers here.

"Hot Spring Tales" its a side story about 3 girls talking to each other about themselves and the rest of the cast while being at the hot spring. Requires you to finish pretty much all events possible with side characters (you don't need all events from the main heroines) in order to not be spoiled by it (new game+ chars not included in the spoilers there; so if you did everything in your 1st run, you can do this extra story and get no spoilers, its more like a "review")

what they say and if u meet all the special requirement(bonus) u get something special .....

Also, sex.