Since June 2015, iPhone supports iBooks Author format in iBooks.
Due to this change, E-SAKUGA became available on iPhone. Various features including Tapmation™ are 100% intact. However, due to Apple’s specifications, how iBooks Author books appear/work on iPhone is different from iPad.
Each action is performed in a separate window for iPhone, so E-SAKUGA’s seamless operation between checking the key frames, time sheets, and reference videos simultaneously cannot be done in iPhone. Please have this in mind if you intend to view E-SAKUGA with your iPhone.
Added on October 2016:
Since iOS10, Tapmation™ works as intended also on iPhone.
Tapmation™ does not open a new window anymore and works seamlessly like on an iPad.
However, still images will prompt a new window like before. We cannot view all elements on one screen seamlessly like on an iPad.
The still image in iPad is operable by just tapping the screen, but on iPhone each element operates on a different window. Thus, we cannot see the time sheet and key frames together.