This is an English translation of the Custom NPC mod created by KYM2020, who was given permission by the original mod author to translate it and then they gave me permission to upload their translation. The original mod by Mihibi shuki is over here.

A brief introduction (that I copied and pasted from the original mod page):
Thurstan claims to be a traveler who came to Stardew Valley accidentally. After meeting you for the first time, he will take a bus to town every day. His life background is unknown. It seems that he is very taboo to talk about his past. However, after his popularity gradually increases, he will reveal his heart to you
Go and be his only "best friend", he is waiting for you.



Events:
0 ❤： After four days of gameplay, come to the mountain where Robin's house is located at 13:00-17:00 on any day other than Tuesday on Spring (or Tuesday in any season if you use the updated event.json file from the Updates section).
2 ❤： From 17:00-20:00 on Monday or Tuesday in the first year, go to Cindersap Forest.
4 ❤： Except on Sundays, got to Cindersap Forest from 15:00 to 18:30 on rainy days.
6 ❤： Come to the beach at 8:00-14:00 on a sunny day on Tuesday, Thursday or Saturday.
8 ❤：
① Come to the forest under the farm at 21:00-24:00 on Sunday evening.
② After watching the event ①, go to the bus stop at 16:00-18:00 on Sunday afternoon.

It was originally possible to miss his first two heart events if it's not the first year, but I edited that conditions out.

If you have a more accurate translation of this mod or if there's any grammar or spelling mistakes or any bugs, please mention them.

Update: He won't show up in the game right away, you have to see his intro/0-heart event and then he shows up the next day at the bus stop.

FAQS:
CAN I MAKE A TRANSLATION BASED OFF THIS TRANSLATION?/CAN I EDIT THE JSON FILES?
I wasn't the one who did the translation, I only did most of the proofreading and some of the more technical things. Not to mention, it's generally a bad idea to base a machine translation off a machine translation, so please don't base off a translation off of this translation. Though, I guess that a personal edit wouldn't hurt anyone.

IS THIS COMPATIBLE WITH SVE?
Nope. Though, the author said that they'll create a patch for that. Maybe removing/deleting the Custom Locations section in the Content.json might work, but I never tested their compatibility out otherwise.

WHY IS HIS PORTRAIT ZOOMED IN?
You have to copy and paste his portrait to Portraiture just like how you do with portraiture mods. Or you can use the HD Portraits conversion that I uploaded in the files.

OMGEEE WHAT MODS ARE YOU USING IN THAT SCREENSHOT?
- Project Yellog (the old version of it)
- Stardew Valley Reimagined 2
Farmer  (most, if not all of them, should be in blogs)
- Clothes: ByeolChris's Cloak, one of Delotti's skirts
- Hair: one of kkunma_09's
- Body: GH's Peach Body
- Accessory: GH's eyes highlight
UI
- Overgrown Flowery Interface
- Script Font
- fish's bowknot cursors
- Natural Color - Reshade

CAN I REDISTRIBUTE THIS TRANSLATION?
No.

I DON'T LIKE THAT ANIME ARTSTYLE/HIS PORTRAIT LOOKS OUT OF PLACE/ETC.
The back button is on the upper left corner. Also, I'm not sure if the mod author allows re-textures of their character to be created, but the mod author should be allowed to mod in the style they want.