I read this without the literary analysis magnifying glass that perhaps this story deserves, but I'll give a crack at what I did pick up even just as a casual reader.
Sekine is quite traumatized, and the earlier chapters feel accordingly heavy. But the story kept me reading because you were given hope that the introduction of this quaint knitting-magic-trick shop grandpa/granddaughter pair could do something to change this empty shell of a man. I could relate to Sekine, feeling how sometimes you can pass the time with some hobbies/work but feel nothing at all for it, because you use it to distract from whatever's actually bothering you. I thought the story makes you remember the interesting whimsical little things in life that aren't in the typical office worker's life, from magic tricks to circuses to wool farms, all as it introduces more color to Sekine's dull salaryman life. Sara, the granddaughter, also is a colorful personality in the way she can make mundane things interesting, all a contrast to Sekine who goes through the motions in life.
I think it's hard to describe this more accurately than the journey of a man finding meaning and reason to live and strive, as cliched as that might sound. The author did a fantastic job with illustrating these feelings and his journey through day to day events and interactions. I think one thing the author did well was to convey deeper messages through characters interpreting other characters' off-hand remarks in a way that really strikes a chord. For example, one character explained to Sekine how he would keep trying to win this game of table tennis even if the odds were stacked against him. And Sekine took that as a life lesson to try
pursuing Sara even though she'd been kind of harsh to him
since that was almost the first time things haven't come to him naturally without him seeking it out (he's good at everything and women flock to him). And another example I really like is when
! Kozue talks about handmade creations as a sort of extension of the creator and how interacting with these objects is a subconscious desire to be closer to them, and that's when Sara realizes the excuses she's made to herself are all false because she actually does have feelings for Sekine.
Overall the story is perfectly enjoyable even if you don't read it into it too much, because even just reading on a plot level I found all the situations very realistic and relatable.