Koisuru Asteroid - Vol. 5 Ch. 59

[MangaDex]

 

[Nine_Gates]

"Hornfels" and "Feldspar" also happen to be names of characters in the space exploration game Outer Wilds. All Hearthians in the game are named after rocks. Maybe the mangaka put in a reference to it?

 

[KevN4968192]

"Hornfels" and "Feldspar" also happen to be names of characters in the space exploration game Outer Wilds. All Hearthians in the game are named after rocks. Maybe the mangaka put in a reference to it?

Can't say for sure but it's possible to be the case