What does バックパック look like on HTC?

On HTC it is the design shipped in Sense 8, shown above at full size. Older revisions are listed beneath it.

When did HTC add バックパック?

HTC first drew バックパック in Sense 7, released 2015年3月30日.

HTC Corporation has shipped 2 versions of バックパック. Each is dated, so you can see when the design changed.

HTC

HTC Corporation has drawn バックパック 2 times. Every revision HTC has shipped is below, newest first.

What does バックパック look like on HTC?: On HTC it is the design shipped in Sense 8, shown above at full size. Older revisions are listed beneath it.
When did HTC add バックパック?: HTC first drew バックパック in Sense 7, released 2015年3月30日.
How many times has HTC redrawn バックパック?: HTC Corporation has shipped 2 versions of バックパック. Each is dated, so you can see when the design changed.

HTC artwork for this emoji spans 2015 to 2016.