About the Authors

Takumi Yokosaka

yokosaka.takumi@lab.ntt.co.jp

Affiliation NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation, Kanagawa, Japan

Scinob Kuroki

Affiliation NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation, Kanagawa, Japan

Shin’ya Nishida

Affiliation NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation, Kanagawa, Japan

Junji Watanabe

Affiliation NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation, Kanagawa, Japan

Competing Interests

This work was supported by Nippon Telegraph and Telephone (NTT) Corporation, the employer of all authors. There are no patents, products in development or marketed products to declare. This does not alter the authors' adherence to PLOS ONE policies on sharing data and materials.

Author Contributions

Conceived and designed the experiments: TY SK SN JW. Performed the experiments: TY. Analyzed the data: TY. Wrote the paper: TY SK SN JW.