快男児 - nice guy
As in, a guy who is actually nice, or the sarcastic “nice guy” that refers to someone who is actually not? 
I genuinely want this to be sarcastic, because 怪人二十面相 is serving me so many old-school phrases no one uses anymore (not to mention the crippling keigo of the main villain…) that I’m again close to bailing out.
Goo has this to say
性質がさっぱりした気持ちのよい男。快活で男らしい男。好漢。快男子。
So like… an actually fine fellow 
快活で男らしい男。 one can’t be more 男ほど than an 男らしい男
自然、しぜん、nature; natural
i learned it earlier today
多目的室・multipurpose room
Map reading ability level up!
ゼリー / ジェレ both mean jelly
Thursday night fun with numbers
一段 - even more, still more
万一 - worse case scenario, one in a 10000 chance
While you’re at it, it might be worth familiarizing yourself with the more common form, 万が一
Oh heck, thank you so much! 
Yes, the book I’m reading is a little mushy (first edition in 1938, I think).
夕焼け-ゆうやけ- Afterglow (of sunset), evening glow
It just makes so much sense, what a fantastic way to describe it.
飯テロ - food porn (as in really nice pictures of food)
繁忙・煩忙・繫忙期
Since the last one is suggested by IME, and Yomichan failed to pick it up due to the odd Kanji, I decided to look the word up. The Kanji appears to be from 繋がり, but in old form.
目の保養 - feast for the eyes; and then I found another one - 目の正月
学問の自由: Academic freedom. I learned it from No Regrets For Our Youth.
虹 - rainbow (I saw it the first time playing ナイツクロニクル. One of the upgrade monsters was called 虹モン and I thought it’s read え cause it was one to bump experience, but apparently not)
豪胆 - daring, bold (if I were to learn both kanji on WaniKani that would make for a funny “daring gall bladder” combo based on the kanji meanings - if WaniKani actually used the correct meaning for 胆, which it doesn’t)
絨毯 - carpet
Half expected you to know that one already - what with 虹サンジ 
Mind.blown. I had no idea.
Not new to me, but I just like this kanji and thought people would enjoy it.
虱 - louse; lice
蒸発 - evaporation
鍵穴 - keyhole
大商人
おおあきんど
Wealthy merchant
Which is an interesting reading since 商人 has been showing up pretty regularly in the word 行商人 but with the しょうにん reading. But that led to also learning the following:
商う
あきなう
To trade in (commercial goods)
正夢 - a dream that comes true
Really liked this one!