List: word usually written using kana alone

archaic  usually written using kana alone  noun  noun (generic) 

• prostitute and entertainer

rarely used kanji form  usually written using kana alone  noun  noun (generic) 

• cleaning out mud from a ditch or drain

usually written using kana alone  noun  noun (generic) 

• Volvox (genus of green algae)

popular  search-only kanji form  usually written using kana alone  expression 

• have to (verb), must (verb)
• is indispensable, is absolutely necessary

usually written using kana alone  expression 

• anyway, by the way, incidentally, well, to change the subject

noun  noun (generic)  mathematics  usually written using kana alone  abbreviation  prefix 

• R, r
• radius
• curve, rounding
• nth year in the Reiwa era (May 1, 2019-)
• refrigerator

gairaigo  Chinese origin  usually written using kana alone  food, cooking  noun  noun (generic) 

• Chinese-style stir-fried vegetable noodle soup

usually written using kana alone  prefix 

• faintly, dimly, slightly, barely

usually written using kana alone  noun  noun (generic)  colloquial  dated term 

• upside-down jellyfish (Cassiopea ornata), jellyfish of the genus Cassiopea
• traditional love hotel, traditional Japanese inn specially for couples

usually written using kana alone  colloquial  godan verb  godan verb (archaic)  verb (generic)  intransitive verb 

• to be mixed up with, to have a connection with (a troublesome matter)
• to be a stickler about, to be finicky about (some triviality)
• to take part (in some work), to hang about, to bother (someone)