Here is the full list of all 49 BLUE REFLECTION: Second Light achievements.
Defeat "The World."
Get all characters to level 50.
Create Origin Gate.
Get Ao to level 50.
Recover Uta's memories.
Collect all memory shards.
Recover Yuzu and Lime's memories.
Go on 100 dates.
Recover Yuki's memories.
Fulfill 50 requests.
Develop 30 facilities.
Defeat "The One Who Came from Nothing."
Craft 50 different items.
Recover the Hirahara Sisters' memories.
Access 10 different school facilities.
Go on 50 dates.
Develop the bath.
Recover Kirara's memories.
Fulfill 25 requests.
Develop 15 facilities.
Go on 25 dates.
Craft 25 different items.
Recover Rena's memories.
Activate Ether Tide for the first time.
Defeat "The One Who Fell from the Sky."
Recover Hinako's memories.
Use an item to remove an obstacle from a path for the first time.
Recover Shiho's memories.
Activate a One-on-One Finisher for the first time.
Develop a facility for the first time.
Go on a date for the first time.
Recover Kokoro's memories.
Cut grass 50 times.
Repair the leak at the school.
Fulfill a request for the first time.
Craft an item for the first time.
Obtain all Achievements.
Raise Ao's Talent level to maximum.
Raise Kokoro's Talent level to maximum.
Raise Rena's Talent level to maximum.
Raise Yuki's Talent level to maximum.
Raise Shiho's Talent level to maximum.
Raise Hinako's Talent level to maximum.
Raise Kirara's Talent level to maximum.
Raise Hiori's Talent level to maximum.
Raise Mio's Talent level to maximum.
Raise Uta's Talent level to maximum.
Activate Ether Tide with all characters.
Explore all locations.