https://www.pcgamer.com/from-software-explains-why-its-working-with-activision-on-sekiro/

In the wake of its impressive E3 showing, From Software said Activision is giving the studio "much-needed support" on Sekiro's tutorial system. The partnership still strikes me as an odd one, but the Dark Souls studio has opened up on why joining forces with the publisher is the right move.  

Talking to gamesindustry.biz at Gamescom, From's community manager Yasuhiro Kitao says Activision was one among many western publishers it pitched Sekiro to.