[8] Reviewing the album for AllMusic, Paul Simpson compared it to Sakamoto's previous work.

Simpson claimed that, "While [async] was an inventive, ambitious work incorporating field recordings, spoken word vocals, and several guest musicians, 12 is considerably more stripped-down, created entirely by Sakamoto, mostly playing piano and synthesizers."

Simpson concluded by stating that, "being aware that it was his final work adds emotional weight to music that appears fragile and delicate.

"[9] In a review for The Skinny, Tony Inglis awarded 12 a 5-star rating and noted that unlike Sakamoto's previous works, 12 is a "collection [that] instead deals in the turbulent and unpredictable period that comes before the unknown.

"[14] In a positive review for Pitchfork, Rob Arcand highlighted how "Rarely does an album this understated say so much.