The hidden achievement mission of Subway Blossoms is located on the first platform. We can investigate the box and get prompt information.
After clearing the basic plot, return to the original platform and the suitcase on the ground has been opened.
Investigate the suitcase, unlock the station map, and the letter prompts us to go to Rusty Lake Station.
Arriving at Rusty Lake Station, the NPC on the bench asked us to collect cubes and start a hidden mission.
