Even though she only had a year or so of collaborations under her belt at the time of this debut album, Thelma Aoyama had already established herself as a force to be reckoned with in the ranks of J-soul artists. After a breakthrough single in conjunction with rapper Soulja, "Koko Ni Iru Yo," Aoyama recorded a response, "Soba Ni Iru Ne," which included not only Soulja himself but also the same chorus. With a stronger bent toward R&B vocals and a reduction in the force of rap on the single, Aoyama was fast-tracked as a major artist, quickly becoming the most downloaded artist with the single of the year in Japan. That song is the centerpiece of Diary, and a fine anchor to center around. In the rest of the album, she touches upon more of an empowered-woman sound, adding force to her vocals and a Whitney Houston-esque tinge to her delivery. The compositions are largely pedestrian fare, basic bits of a pop/R&B hybrid that bounces between English and Japanese with incredible ease but stays in the sweet spot of R&B. Where the album shines is Aoyama's vocals. She can lilt sweetly, she can strain powerfully, she can occasionally go into the requisite J-pop falsetto. Regardless of the track, she finds the right vocal approach to bring to the table. The sound might not be groundbreaking in and of itself, but a nice listen all around is here to be had.
AllMusic Review by Adam Greenberg