▪ The name of the event is Strawberry Picking, but the chapters of the story are labeled as "Strawberry Colored Holiday"
Titles and Honorifics
-dono: That honorific that particularly humble or traditional characters use. If you watch anime that are set in the Meiji era (or older) you may be familiar with this. Shinobu uses this since he's a ninja otaku, as does Souma, as he's the traditional type.
Character Speech Patterns
Shinobu tends to speak in somewhat archaic forms, while simultaneously sounding childish (he's fond of onomatopoeias, for example). He likes to use sessha (a humble and old way of referring to yourself), and even uses some old forms (such as using -nu instead of -nai for negatives). These are really hard to portray in translations outside of making him speak as humble/polite/archaic as I could, so I'm mentioning them here.
Chapter - 1:
Sunflower is 向日葵/Hi・ma・wari. The last character is the same as the twins' last name 葵/Aoi. So I guess he's kind of right...? Also in the succeeding line, he says Sunflower in katakana
Chapter - 2:
Mini 4WD (ミニ四駆) is a small miniature race car that runs on batteries without a remote control. They were highly popularized in Japan by the Tamiya Corporation (hence the censor))
Chapter - 5:
Zashiki-warashi is a child-like spirit that resides in good, large homes. Its presence is said to bring good fortune to the household.
Chapter - 8:
A kusarigama is a weapon composed of a chain and a sickle, which is what the name literally means, from 鎖/kusari (chain) and 鎌/kama (Japanese sickle). Obviously, it is a weapon favored by ninjas.