Why? Like, what do the words in the clue mean?
Think you’re over-thinking this one - グラブ works just fine, and has the added advantage of making 3-across ラブ
2-across クライマックス
(which makes 27-down アス)
29-across クルマ? Because there aren’t any trains?
32-down リサイクル
(which makes 28-across タサン)
25-across ガラクタ
35-down タマムシイロ (I don’t really get it, but it fits)
(which makes 33-across コシ)
Words in the clue didn’t mean much. The answer was in the page you referenced. 
ひさかたの 日・空など天体に関する語にかかる枕詞（まくらことば）
edit: 16 across ワカイ
19 down フツカヨイ
Ah, whoops, I forgot to come back to this. Just a few boxes left empty.
20-across イサカイ
18-across ブドウ… I guess?
That’s everything done, in any case. Gonna have to wrap things up in the morning, though.
I can tell this is gonna be another slow crossword. 
22-across イヤリング
39-down グリップ
36-across キリ
35-down ネンキン
32-across パンツ
32-down パッション
27-down ヤド
18-across カマド
A crosslink to the crossword thread.
https://community.wanikani.com/t/descent-of-the-durtle-into-egoooott-now-at-b8/34318/8816?u=xxllua
Also, I’ve discovered an app on the Play Store full of Japanese crosswords, if anyone’s interested.
I just downloaded the app. Wow, I do not speak Japanese well enough for this. But it’s a nice challenge.
Aye, I discovered the same with my paper book. It’s like, even if I can read the clue, I still need to know the answer. 
Anyone have any tips on 「海苔巻きの具の定番」? Five characters, likely starts with カン.
I misunderstood the clue, thought it was something used to make norimaki. It’s something that’s in norimaki.
Try the across clue in the third row. My tip for that one: don’t overthink it.
I’m only missing the bottom right six slots now 
Thanks.
Oh let’s resurrect the crossword thread on the hard puzzle. 
That being said
11-across ソウビ(?)
15-across シュワ
26-across クチゲンカ
31-across アネ
38-across ワニ
18-down カユ
19-down ビン (?)
24-down テイショク
31-down アリ
34-down アゲ
38-down ワイン
40-down シンニチか
アネ. It’s 妹のライバル not 弟の.
Wait, lemme draw up the in-progress grid. Been a while since I did this last…
Well I’m glad you’re familiar with the various types of rice porrige, because I wouldn’t have had the foggiest idea.
yea that’s what i meant lol
and okayu is surprisingly delicious for being nothing but watery rice.
AWS image host seems to be borked right now, so in-progress grid will have to wait.
In the meantime:
15-down ショウグン
16-across グンテ (it’s a pun…)
Edit: Here we go
There are several missing. Scroll back up to my list. lol I had kept adding why you were putting that together.
Oh, sneaky. Here’s a new grid. I’ve also updated the Google sheet.
So, I see that 26- and 38-across are the only things they can be given the cross letters, but I’m not too clear as to why.
More words!
33-across ヨウシ
8-across ダツイジョ
13-across ヒナ
(17-down イナ)
12-down キミツヒ
I’m going away this week. I’ll be taking my book with me, but I’d be surprised if I got the time to look at it.
I like that you’re still enthusiastic about this. I just wish others were a bit, too…
Anyway:
1-across ラッカセイ. Cause of the narrow waist, ya know. And honestly thought “peanuts” was ピーナッツ in Japanese. Though, I guess it’s that too. But the point is,
14-down カズ
21-down イイマワシ
2-across クイズ
Making 9-across ツイン, which in hindsight should have been obvious
1-down ラクテンカ
10-down キソ
Makes 4-across シキョ, I guess, but I only kinda get it
And whoever guessed ソウビ for 11-across was correct.
That leaves four empty boxes. Four clues.
Edit: Actually, the super secret magic word can only be マンネンヒツ, which makes 23-across シマウ
