https://bgp.he.net/AS31399
From what I have researched, it doesn't look like they use it. There are not too many /8 subnets, "owned" only by one company, too. Softbank also has one.
A more detailed list can be found at: https://en.wikipedia.org/wiki/List_of_assigned_/8_IPv4_addre...
Show HN: Mercedes-Benz Group AG owns an IPv4 /8 subnet
ipinfo.io