Here is a list of my suggested posts to dive into:
Column
Ambiguity in Japanese: How and Why We Omit Words, Phrases and Clauses in Japanese
奈良 (Nara): A Beautiful, Traditional and “Deerest” City in Japan
Why “The moon is beautiful” Could Mean “I love You” in Japanese
What イチロー (Ichiro Suzuki) Means To Us Japanese People
How to Memorise Japanese Kanji Efficiently with Radicals
“Read the Air and Hold Back”: Japanese Words Mirroring Japanese Mindset
Idiom
三日坊主 (mikka bouzu) ‘Three-Day Monk’ in Japanese Idiom
高嶺の花 (takane no hana): Girls like a Beautiful Flower at the Top of a Mountain
サバを読む (saba wo yomu): “Read Mackerels” in Japanese Idiom
はしごを外す (hashigo wo hazusu): Idiom Meaning Unexpected “Betrayal”
猫をかぶる (neko wo kaburu): Japanese Idiom ‘Wear a Cat’
Slang
11 Bizarre Japanese Slang Words Untranslatable Into English Words
雰囲気イケメン (fuinki ikemen): ‘Handsome-Vibe Men’ in Japanese Slang
黒歴史 (kuro rekishi): ‘Humiliating Memories in the Past’ in Japanese Slang
高校デビュー (koukou debyū): Japanese Slang ‘High School Debut’
ザギンでシースー: Japanese “Reverse” Slang From 1980s
自粛警察 (jishuku keisatsu): Japan’s “Self-Restraint Police” Explained
Words/Idioms by Theme
“り” means “I got it” – 30 Enigmatic Abbreviations in Japanese
Yes, There’s a Word for It – 20 Japanese Expressions with Specific Meaning
12 Japanese Words Rooted in 茶 (cha) and Japanese Tea Cultures
8 Funny Japanese Idioms Related to ‘Cats’ (猫, neko)
20 Japanese Words, Idioms and Onomatopoeia Related to Rain (雨, ame)
9 Essential Words in Kansai-ben with Detailed Usage Examples
11 Japanese Idioms and Metaphors about Baseball (野球, Yakyū)
Grammar
Differences Between Location Particles に (ni) and で (de) in Japanese
Essential Grammar in Kansai Dialect (関西弁, Kansaiben)