Here is the full list of all 52 Bullet Hell Monday achievements.
Played Extra mode.
Cleared Challenge 3 without using continues.
Cleared 404 in Chapter 4.
Cleared Chapter 3.
Cleared Challenge 2 without using continues.
Cleared Chapter 2.
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.
Got an extra life.
Played Challenge mode.
Cleared Chapter 1.
Completed the tutorial.
Played Chapter mode.
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 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.
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)
Cleared without using bombs. (Challenge, any stage, Normal or above)
Cleared with No Deaths and No Bombs. (Challenge, any stage, Normal or above)
Reached a score multiplier of 9999.9%.
Cleared without losing a life. (Challenge, any stage, Normal or above)
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)