Dr. Yamaguchi is approachable enough to encourage students to ask questions without breaking into the "unprofessional" end of the scale. He is on time, organised in regards to material and able to competently explain the content. The only downsides to having him as a lecturer is his handwriting, which while fast is fairly messy, and his occasional inability to work technology (it's not like that is a unique problem though).
He also makes himself available outside of class time on days that he teaches. Excellent lecturer, would recommend.