Head Smoke

In manga and anime, sometimes smoke is drawn coming out of a character's head or ears when they're thinking too hard, when they're embarrassed, or when they're angry, fuming.

Left: Kumai Natsu クマ井ナツ
Right: Amayadori Machi 雨宿まち
Anime: Kuma Miko くまみこ (Episode 1)

• Examples

Examples

For reference, some examples of smoke coming out of characters' heads:

Character: Ayase Chihaya 綾瀬千早
Anime: Chihayafuru ちはやふる (Episode 11)

• kemuri
  煙
  Smoke.

Left: Fujiwara Chika 藤原千花
Middle: Shinomiya Kaguya 四宮かぐや
Right: Shirogane Miyuki 白銀御行
Anime: Kaguya-sama wa Kokurasetai ~Tensai-Tachi no Ren'ai Zunousen かぐや様は告らせたい～天才たちの恋愛頭脳戦～ (Episode 1)

• yuge
  湯気
  Steam. Vapor.

Character: Ogata Rizu 緒方理珠
Anime: Bokutachi wa Benkyou ga Dekinai ぼくたちは勉強ができない (Episode 1)

• fukurettsura
  ふくれっ面
  Pouting face.

Character: Edward Elric エドワード・エルリック
Anime: Fullmetal Alchemist: Brotherhood, Hagane no Renkinjutsushi 鋼の錬金術師 (Episode 1)

• A forehead shadow, triangle eyes, jagged teeth, and popped veins, anger marks, are other symbols that this character is angry, besides the smoke coming out of his nose.

Character: Aisaka Taiga 逢坂大河
Anime: Toradora! とらドラ！ (Episode 10)

Although rather unusual nowadays, black smoke swirling over a character's head like a tornado generally symbolizes anger and frustration.

Character: Hiruzen Sarutobi 猿飛ヒルゼン,
Manga: Naruto ナルト (Chapter 2, 木ノ葉丸)

If the smoke comes out of their mouth, that's probably a sigh instead.

Character: Aioi Yuuko 相生祐子
Anime: Nichijou 日常 (Episode 1)

Unless it's their soul coming out of their mouths.

Character: Dino ディーノ
Anime: Blend S, ブレンド・S (Episode 5)

Or a snot bubble coming out of their noses because they're sleeping.

Left: Reina レーナ
Right: Mile マイル
Anime: Watashi, Nouryoku wa Heikinchi de tte Itta yo ne! 私、能力は平均値でって言ったよね！ (Episode 10)