Here is the full list of all 52 Bullet Hell Monday achievements.
Cleared Challenge 2 without using continues.
Got an extra life.
Cleared Challenge 1 without using continues.
Obtained grade A or higher in Challenge or Extra mode.
Obtained grade S or higher in Challenge or Extra mode.
Cleared without using bombs. (Challenge, any stage, Normal or above)
Cleared with No Deaths and No Bombs. (Challenge, any stage, Normal or above)
Cleared without losing a life. (Challenge, any stage, Normal or above)
Played Challenge mode.
Cleared Chapter 3.
Cleared Chapter 2.
Cleared Chapter 1.
Played Chapter mode.
Completed the tutorial.
Cleared Chapter 4.
Cleared Chapter 5.
Cleared Chapter mode.
Completed all missions in Chapter 1.
Completed all missions in Chapter 2.
Completed all missions in Chapter 3.
Completed all missions in Chapter 4.
Completed all missions in Chapter 5.
Completed all missions in Chapter mode.
Cleared Challenge 3 without using continues.
Cleared Challenge 4 without using continues.
Cleared Challenge 5 without using continues.
Cleared Challenge ALL without using continues. (Normal or above)
Cleared Challenge ALL on Heaven difficulty without using continues.
Obtained grade U or higher in Challenge or Extra mode.
Obtained grade U++ in Challenge 1.
Obtained grade U++ in Challenge 2.
Obtained grade U++ in Challenge 3.
Obtained grade U++ in Challenge 4.
Obtained grade U++ in Challenge 5.
Obtained grade U++ in Challenge ALL.
Played Extra mode.
Obtained grade U++ in Endless 1.
Survived for more than 30 minutes in Endless 2.
Obtained grade U++ in Accel 1.
Survived for more than 30 minutes in Accel 2.
Survived for more than 60 minutes in Extra mode. (Any stage)
Reached a score multiplier of 9999.9%.
Cleared 404 in Chapter 4.
Cleared Challenge ALL with only the Laser type. (1CC, Normal or above)
Cleared Challenge ALL with only the Wide type. (1CC, Normal or above)
Cleared Challenge ALL with only the Phantom type. (1CC, Normal or above)
Cleared Challenge ALL with only the Homing type. (1CC, Normal or above)
Cleared Challenge ALL with only the Shielding type. (1CC, Normal or above)
Cleared Challenge ALL with only the Time type. (1CC, Normal or above)
Cleared Challenge ALL with only the Search type. (1CC, Normal or above)
Cleared Challenge ALL with only the Lock-On type. (1CC, Normal or above)
Cleared Challenge ALL with only the Blade type. (1CC, Normal or above)