TL;DR: Join the campaign via the above page>Play DMM game everyday>Get free DMM pts and Amazon gift card on 22 May if you are lucky

Basically, the event is on between April 6 to May 11, and you need to meet the following login requirements in order to get free items and join the lottery for DMM pts and Amazon gift cards:

1st chance: Within 10 days of the day you join the campaign (i.e. April 6-Apr 15), login 5 days (among which 3 days have to be consecutive)

Bonus chance: Once you meet 1st chance's requirement, within 15 days of the day you clear 1st chance's requirement, login 10 days.

You will get free items and chance to join a lottery for DMM pts (500pt x10000 for each round) and Amazon gift cards (1000yen x500 for each round) once you fulfill the requirement for each round.

Items, pts and gift card will be distributed by May 22.