Today I recommend Sousou no Frieren by author Kanehito Yamada and artist Tsukasa Abe.
This is quite possibly one of the best manga I've read. It's a tale of the unflinching progression of time, understanding loss as a near immortal being, and being able to rekindle and create former connections once thought lost. It's a touching series about coming to terms with the passage of time wrapped up in a beautiful fantasy world.
Highly recommend this series. I look forward to it every time a chapter updates, and it is one of my favorite fantasy manga series. Once I get a stable income again, I do plan on collecting the volumes.