Here is the full list of all 27 Onechanbara: Bikini Samurai Squad achievements worth 1,000 gamerscore.
Cleared Story Mode on BERSERK difficulty
Cleared Story Mode on VIOLENT difficulty
All bonuses for the character "Annna" collected
Completed Quest No.15 "Rampaging Baneful Blood" (LV1~3)
All bonuses for the character "Saki" collected
Completed Quest No.11 "Cool Master" (LV1~3)
Completed Quest No.10 "Swift and Beautiful Death" (LV1~3)
Cleared Story Mode on HARD difficulty
Completed Quest No.17 "Counterstrike Flash" (LV1~3)
Completed Quest No.20 "Arrival in the Abyss" (LV1~3)
Completed Quest No.12 "Zombie Piercer" (LV1~3)
Completed Quest No.7 "Dance of the Empress" (LV1~3)
Cleared Story Mode on NORMAL difficulty
Completed Quest No.8 "Combo Death of the Empress" (LV1~3)
Completed Quest No.9 "The Untouched Empress" (LV1~3)
All bonuses for the character "Aya" collected
Completed Quest No.18 "Hit & Run" (LV1~3)
Completed Quest No.4 "Insane Libido" (LV1~3)
Completed Quest No.16 "Swallow's Dance" (LV1~3)
Completed Quest No.14 "Height of Ecstasy" (LV1~3)
Completed Quest No.2 "Genocider" (LV1~3)
Completed Quest No.5 "Near Death High" (LV1~3)
Completed Quest No.6 "Bloody Sword" (LV1~3)
Completed Quest No.1 "One Bizarre Woman" (LV1~3)
Completed Quest No.13 "Technical Master" (LV1~3)
Completed Quest No.19 "Rain of Bullets" (LV1~3)
Completed Quest No.3 "Crimson Makeup" (LV1~3)