The first computer storage using perpendicular technology was by IBM. Here's the tech paper on it.
IBM
Seagate released the first commercial HDD product. The answer depends on how "released" is defined.
>>>"INRECOUNTING the history of perpendicular recording for magnetic disk data storage, I will primarily focus on an IBM development project called the Advanced Disk File (ADF). The disk-drive product that emerged was the IBM 1301, which was the first disk drive to embody a flying head per surface, making it the actual precursor of all subsequent disk drives. The historical importance of this drive is that it was the first to support
real time online transaction processing, a capability which revolutionized the computer industry." <<<
This took place in 1955! Seagat e was not even born yet!