Rangidax asked you to find someone who's been doing volunteer work for the Solorius festival.
Step 1. Bring the envelope to 'ZubinerkA Shugo who is taking part in Solorius as a volunteer. Unusually for a shugo, he refuses to get paid, and keeps running between Heart of Impetusium, Basfelt Village, and Altgard Fortress to hide..
Step 2. Take a Solorius ticket to SkaninA hunter who is next to the Mosbear pen at Basfelt Village in Altgard..
Step 3. Take a Solorius ticket to GrakAn Archon Sentinel who assists Gulkalla at the Heart of Impetusium in Altgard. He regrets having come to Impetusium..
Step 4. Report back to RangidaxHe visited Pandaemonium Plaza to organize Solorius. He looks a little tired from all his efforts..