Here are the rankings for the second-year named cast:
5th Nanasaki Ikuo (MC dude’s friend)
10th Sanjou Ruise (red-eyed girl)
34th Kamita Shouichi (MC dude)
36th Tsuneki Hikari (teasing girl)
38th Takato Yukie (Hikari’s short-haired friend)
50th Isomae Manabu (glasses guy that was with beard guy)
130th Kikuchi Yoko (Hikari’s longer-haired friend)
-From Kibitou w/ Love
These are based on the popular candy/snack “Mushroom Mountain” (Kinoko no Yama) from Meiji. The mushroom cap is chocolate and the stem is some sort of cookie-like substance. There’s also a similar candy/snack called “Bamboo-shoot Village” (Takenoko no Sato). They’re basically the same candy, just one is “lump of chocolate with a cookie stick” and the other is “hunk of cookie with chocolate poured on top.” It occupies a similar “basically the same thing but people get worked up about which is better” cultural niche as coke and pepsi in the US.
The company name “Nichigetsu” (日月) comes from breaking the first kanji in Meiji (明) into its constituent parts, sun/day (日) and moon/month (月).
Shiitake are a popular type of mushroom eaten in a bunch of common dishes in Japan.
In Japan, many types of candy (and ice cream, and soda, etc. etc.) release seasonal flavors that have limited runs; Pumpkin Pudding Kitkats around Halloween for example. Presumably this Shiitake Valley is one of these seasonal things, hence the “oh it’s out already!” reaction.
There are also regional variants on top of the seasonal variants. Apple Kitkats around Nagano, Strawberry Cheesecake Kitkats in Yokohama, Citrus Kitkats around Hiroshima, etc. (this trend isn’t limited to Kitkats by any means, but they’re a well-known example).
If you were curious why Kitkats seem so popular in Japan, some of it comes from the fact that the name “Kitkat” when pronounced using Japanese phonemes, sounds like “sure win.” They make good presents for students before a big exam as a result. The company that makes them has at times capitalized on this, going so far as to have special editions with phrases like “you can do it!” printed on the bars.
A yukata is a light kimono, for use in the summer or provided at hotels to be worn after a bath.
A dotera (changed to “kimono” in the subs here) is a heavier/padded kimono typically worn in the winter that can double as an extra blanket as well when draped over a futon. Definitely not something you’re likely to see someone wearing in the summer, hence the surprised reactions.
It’s also loosely associated with shut-ins/hikikomori type characters—or more like they’re associated with it—because it’s a comfy thing to wear when all holed up in your room.
Karubi/Kalbi/Galbi means “ribs” in Korean (where the phrase comes from; it’s a popular cut in Korean BBQ), but it generally means boneless cuts from the flank or plate of the cow (in Japan it typically refers to beef, but it can be pork as well). It’s generally considered relatively expensive and not something you’re likely to eat often outside of special events, but is a super popular type of meat for yakiniku.
Yakiniku (“grilled meat”) as a meal generally refers to thinly sliced, roughly bite-sized pieces of meat cooked over an open heat source. People will use chopsticks to more-or-less eat directly off the grill, which is generally set in the middle of the table. It’s a popular thing to eat as a celebration, like after a baseball game, for a birthday, etc.
This bit is a reference to the NHK, Japan’s national public broadcasting corporation (similar to the BBC in the UK) that runs several TV channels (and airs a lot of anime). As a public institution, it is legally mandated that everyone who owns a device capable of receiving broadcasts must pay a subscription fee.
The NHK has agents that go around to addresses where someone new has moved in and tries to get them to sign up for the subscription payments. They can’t enter your house to check if you have a TV or anything, so if you tell them you don’t have one they’re basically forced to give up on trying to collect payments from you. This has resulted in the agents being extremely pushy, often lying that they have ways of telling whether you have a TV, or asking if you have a cellphone (if you have a phone with an antenna that can receive broadcasts, that counts and you have to pay).