Keisei Bus operate four on the Tokyo BRT routes. Calling the four routes that pass through Shimbashi a BRT is a big call with frequencies of 10-20 mins all day.
They get really heavy loading but the artics seem to appear on the most frequent route that doesn't get hammered as much (due to its 5 minute headway in the AM peak).
Alongside these artics are a mixture of Toyota Sora Hydrogen buses and diesel Isuzu Erga's.
Tokyo BRT (Keisei Bus) (R901) Isuzu Erga Duo departing Shimbashi. by SydneyBusGunzel, on Flickr
Tokyo BRT (Keisei Bus) (R902) Isuzu Erga Duo departing Shimbashi. by SydneyBusGunzel, on Flickr
Tokyo BRT (Keisei Bus) (R903) Isuzu Erga Duo arriving at Shimbashi. by SydneyBusGunzel, on FlickrThe City of Yokohama also operate three artics on the Bayside Blue route. There is some confusion if these are actually Isuzu or Hino engines in them but the rest of the bus is the same under the J-Bus venture.
City of Yokohama Transportation Bureau (9-3513) Isuzu Erga Duo in Shinko. by SydneyBusGunzel, on Flickr
City of Yokohama Transportation Bureau (9-3514) Isuzu Erga Duo at the Cup Noodle Museum. by SydneyBusGunzel, on Flickr
City of Yokohama Transportation Bureau (9-3515) Isuzu Erga Duo in Shinko. by SydneyBusGunzel, on FlickrNoel