Kayo Sensei is a Japanese calligrapher who specializes in offering guided lessons for each element of the Japanese writing system across hiragana, katakana, and kanji. While many textbooks and traditional courses offer some form of writing practice, it can be difficult for non-Japanese people to learn the correct shapes of characters aside from simply trying to copy how they're printed on computers and in books, which can vary a lot from how a Japanese person might write a character.
Kayo Sensei makes the process of navigating Japanese handwriting easy through recorded video and photo tips on Twitter; self-published textbooks focusing on hiragana, katakana, and kanji; as well as both video corrections and a virtual course three times a month. Both her textbooks and tips on Twitter are especially helpful, showing both the broad strokes to achieving the correct shape and balance of each character, and the more precise elements that separate a "good" character from a "great" one.