It's going to be some months before Ran's update. It'll also include a way for you to meet him without the help of Garthoz so you can get to all the content he unlocks as well if you never did his content before.
If you have a save file, or use the story skip before Garthoz comes to town, you can just do his content first before Garthoz comes in. As long as you meet the requirements, all of his content can play before The Order comes into town.
Honestly, while some people hate it, this is why so many people require you to talk to and do other people's stuff, so you would do meet and greet others. The story is told through the interactions you have with everyone that you need to piece together to figure out what's going on what's happening while you are doing other things.
It's different how most games have it but I like writing characters acting separate from the player and making it seem like they're all doing stuff while you're doing stuff with others.
Like Jar and Waffurd for example. You learn they see and know each other, but then learn the closer you get to Waffurd, the more Jar interacts with him and gives him ideas.
It's a different way, and if you don't like a character then you're missing out, but it also makes things simple in a way if you don't think of it I need to speed through x to see y. You just need to go around town, do all of x content, then go to y then go to z. Then when you visit x again, they have new content.
But if you're just speeding through it, very easy to miss others cause the game was made with visiting each character in mind rather than you know the path to unlock all of x's content right now.