I played this last week a little early and typed up my thoughts as I went. Since then I’ve been reading a bit and watching things like Tim Rogers’ video on the game, so I’d like to add on information at the end, but I decided to first post my original impressions as they are.
Note that the final save that you do allows you to load into a menu to look at all the things you had at the end of the game, as well as rewatch the ending. There seems to be a sort of new game + system for carrying over your favorite bug sumo beetles too. Loading this save is the only way to see the final diary entry.
There will be lots of spoilers in everything I have to say, so be warned.
Day 28
Boku tried to enforce gender roles on the aunt and she told him, no, she wants to be a pilot. Good for her. Tried to order a kite but was told it’s too late to get it done in time now. We’re really at the end. Seems you’d need really optimal timing to get all of them done; I didn’t get to try either hardest rank one (and the Boku one of course).
Met Yoshiko on the bridge again and made plans for her to visit Boku one day. I’m sure that won’t happen but it’s a sweet gesture. Realized I’m really out of plans, projects, much of anything in mind to do, and I guess since it’s just about the end just existing here is cool in its own way. I always enjoy seeing Saori so once again I took my usual trip that way. No more cameras, and then… no more Saori. Just a little goodbye note in her place. With Saori and kites done I guess that’s about it for the bee path. I really am feeling some kind of way about seeing everything spell the end of summer one by one. Nothing’s really a monumental occurrence itself but it really is ending. Everything ends. And you don’t tend to realize the last time you’ve ever done something until well after it’s over.
Man I typed all that BEFORE I made it to the hideout and the kids there are clearly sad I have to go. Not sad enough to let me win though! They broke out a real killer bug for king rank this time, didn’t have a chance with my 23 win streak champ. I’ll keep an eye out but I think I might be at the limit of my bug sumo ability.
The professor is back! Most of the questions felt a little silly to ask now but I asked him about drawing in my diary and he did tell me to not feel disappointed if there’s nothing impactful for the day. Probably good advice.
When Boku was acting off at dinner I thought he was bummed out about the end of the trip but he’s sick! Poor kid. His little talk with the aunt was so sweet, then wanting to ask for more comforting but ultimately not following through… and then she does her usual role of telling you about dinner lol. This game is really good, perfect sequence.
Day 29
I thought we’d skip morning exercises! Glad he’s better so quickly. We get so many nice photos of the flowers with cute little descriptions! Again, looking back on everything and finally putting that pin in one of the earliest tasks. After talking to the family and learning that the boy who passed away loved sunflowers, I finally knew what to do for today. It’s very possibly not associated with any real task, but I wanted to see the sunflowers again. Across the tree bridge it is. The end has me feeling more than ever like embodying the spirit of the game and just soaking in these last moments. He already had his last summer, but Boku visited for him one more time.
Spent most of the rest of the day revisiting the rest of that path just to see it, and it was quiet and peaceful. Stopping off at the hideout, we chatted again briefly about my leaving and about how we felt like we had been friends for a while now. Then I tried a new beetle I caught today, and it sucked, haha.
Yesterday the glasses boy in the hideout told Boku he thought the baby would be born today and he was right! Again the presentation is so good, hearing Moe playing happy birthday while it shows a little nature scene is beautiful.
I imagine these last days we’ll be seeing the same diary entries. I like Boku dealing with the conflicting emotions of endings and new beginnings all at once.
Day 30
Well this is our last real day here. I had been hoping Shirabe would spend a day with us because she obviously really likes having Boku around and here it is. Honestly I’ve been good about letting this playthrough be imperfect, stumbling onto what I do (probably got some extras I wouldn’t have spotted from everyone else’s posts)… but I’m not going to not find Shirabe today, no way. So I got too curious and checked the guide. Kinda kicked myself once I did and saw it was the sunflower field; the game has been laying on the hints between her talking about it and the dream. Maybe it’s good I checked anyway because there’s a time element so if you get here too early (like I did by coming straight here) you might think it’s simply wrong. Ultimately she was her usual defiant self in that scene to cover up her real thoughts. But when she came home she gave Boku a present and it’s so cute.
At night the aunt told me how she gave up on one of her dreams for the life she settled into now, but having this family has made her happy and fulfilled in its own way. Everyone’s really getting emotional over everything. Shirabe’s not even watching TV, she’s sitting in the dark in the hall.
As a reward for finding Shirabe, Moe let me cheat and stamped the exercise day I missed, so the card is complete, hahaha. Love that.
Day 31
I really liked the quick stop to look at the house one last time when Boku was leaving the kitchen. And aww, him getting the hug and crying… really sweet game, that moment kinda hit me. And Shirabe running after as he gets driven away… 
Post-credits Ending
So, I don’t know anything about the possibilities, but based on how many “events” you saw, there are apparently 5 endings. Very curious to hear what you all get. Honestly, because of the way cutscene mixing with his monolog is I couldn’t make out almost anything in it, but he seemed to be doing pottery like his uncle? It’s the same ending as in this person’s playthrough at the very end of the video https://www.youtube.com/watch?v=0AaYYAp0Clo
I tried searching for a collection of the endings but didn’t find anything on Youtube; if anyone finds that or at least a description of them or anything I’d love that.
Later information I've gained
I haven’t quite finished the Tim Rogers video yet because it’s so long, but he talks quite a bit about a few of the endings in it. What I got was the 4th of 5 (as in, second “best” by event count). The narration I’m struggling to make out is Boku saying he worked at an office job for a while, before eventually quitting to do a pottery apprenticeship with his uncle. That’s really sweet! Kinda feels like the more events you saw, thus the more memorable your trip was, the more it impacts you later in your life. I’m not sure right now what ending 2 and 3 are, but he’s mentioned that the best ending sees Boku as a famous writer having written about his なつやすみ and about to meet Moe and Shirabe who have traveled to visit him. Meanwhile the ending for doing just about nothing over the trip has Boku working in an office, reminiscing on his time sometimes and thinking he should visit or whatnot, but being too busy to ever get around to it. Too real.
Learning more has given me an appreciation for some of the hints I missed, events I could’ve seen if I was most proactive and generally a respect for how… tightly wound it all actually is. The timing for kites and bug sumo seems really strict, and bug sumo has seemingly way more going under the hood to determine the matchups than the game lets on. There’s also so much that’s more limited and complicated than you’d expect, bugs allegedly realistically being replaced by other species as the season wears on and some being only available for a short time in one place for example. I never got to see てっぺん山の秘密 so who knows, maybe one day I can come back and try for it. But I went into Boku with the mindset that summer vacation would happen the way it did and that would be that, so honestly, having an imperfect one feels right for now. And on that note…
My thoughts on the game
I’ve written a sort of long form review already on my Backloggd account and I’d be thrilled if you feel like spending the time to read it.
Daisoujou's review of Boku no Natsuyasumi Portable: Mushimushi Hakase to Teppenyama no Himitsu!! | Backloggd
In summary if you’d prefer, ultimately the crux of it is this: I went in with very high expectations given the reputation this game has and I found a lot to adore in the characters, the visual presentation, etc. That said, in the back of my head there was a frequent feeling like I was appreciating it but wasn’t fully getting the magic the way people do. At times the tasks get a little monotonous or the events kind of esoteric (some do just randomly happen in fixed locations on specific days only with no indication) and I mean I think we can agree for the most part the gameplay isn’t conventionally going for “fun.”
But just like some films I’ve really loved, those last days hit an exact right sense of catharsis to fill everything leading up to it with increased meaning. I was truly going to miss everyone and everything out here in the 田舎 when I had to go home! Some appreciation is only coming retroactively but I can’t think of it as anything but a beautiful little game, now.
Also, here are my bugs
Game Club
All the sunflowers disappeared (representing the passed older brother? amongst other things?)
hehehe