Summer hiking advice for first timer in Japan

Hiya, I am headed to Japan for the first time in mid June to mid July. I will be attending a conference for 5 days in Hokkaido then plan to travel south.

I will be travelling solo for most of the trip (except for the conference, plus partner intending to join for roughly 1 week).

I intend to do a number of day hikes on my trip but I'm looking to do a multiday hike (3-7 days). I've seen info on the Kumano Kodo and the Nakasendo trail. As I will likely be alone for these hikes, I'm thinking of going with a tour. Although I am not having much luck finding tour companies, nor ones that cost less than 1000$. I will be travelling on a budget but willing to splurge for safety. Comfort is not a concern, camping would be ideal! I am an experienced hiker.

I'm wondering if anyone has any recommendations or advice? What hikes are safe to do alone, where can I find likeminded people to hike with etc :)

I have done very little planning thus far as there is lots to see! I was thinking roughly 1-2 weeks in Hokkaido (minus the conference - 5d). I would love to see a brown bear or crane, wildlife watching is a huge passion of mine! Then 2-3 weeks to explore the island(s) south.

I'm very keen to do the 'Japan must do's', but also quite keen to go off the beaten track and do some less touristy things. What would you guys say is a MUST?

Any advice would be greatly appreciated!