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Dangerous beat agents.

Get 1337 combo (break combo after getting it). Not all maps work.
supercell - Kimi no Shiranai Monogatari unlocks this achievement.

Miss the first reverse slider (3 combo lost in total), get 1337 combo and miss note 6 as shown in this video
You should have 1211 combo on your first map break. If you don't - you missed a slider end.