True-or-false quiz for adults: a full roundup from common-sense questions to surprising trivia!

Keyboard playerSAKI
I’ve been playing the Electone since I was six, mainly performing Disney music, anime songs, and music from dramas and films. I post performance videos on YouTube and social media, and I also give concerts. Building on my Electone experience, I took up synthesizer and piano during my student years and performed at school-sponsored events. As a writer, I’ve covered not only music-related topics but a wide range of genres, so I hope to draw on my experience to deliver articles that make readers think, “I want to try that!” or “I want to listen to that!”
Accompanist / Piano Instructoryuri
Accompanist pianist × piano instructor × web writer. I began piano lessons at age four and, inspired by my piano teacher, decided to pursue music. I went on to specialized music programs in high school and university, where I discovered the appeal of accompanying instrumentalists and singers. Currently, alongside teaching piano, I work mainly in my home region of Aichi as an accompanist for flute, voice, choir, and more. Through lessons, my students often introduce me to trending songs, and my hobby is trying anything on the piano—Japanese and Western pop, commercial jingles, and beyond. Since 2021, I’ve also been active as a web writer, covering music and a variety of other genres.

Did you know that hidden within the things we take for granted in our daily lives—things we casually use without a second thought—are actually some astonishing facts? From the unit used for a computer mouse, to the origin of SOS, to the history behind the tally mark “正” used for counting, everyday items are full of surprising truths.

We’ll introduce adult-friendly life trivia lurking in the everyday, presented in a true-or-false quiz format.

We’ve gathered questions that will make you think, “Wait, really?” as well as trivia you’ll be proud to brag about.

So, how many can you get right?

Everyday Life Trivia Quiz (11–20)

The word “gussuri” means “good sleep.”

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Explanation of the answer: The Japanese word “gussuri” describes sleeping deeply and peacefully, and it is not derived from the English phrase “good sleep.” This word is a uniquely Japanese onomatopoeic expression without a specific etymology.

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Hoshino Takashi

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A gift given to express a year’s gratitude to those who have helped you is called “ochūgen.”

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A gift given to someone who has helped you over the past year is called “oseibo.” The word “seibo” means the end of the year. It varies by region, but such gifts are generally sent from early December until around Christmas. By the way, “ochugen” is given in the summer.

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SAKI

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The name Mercury was given because, when it was discovered, it appeared to shine with a light blue color.

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The name Mercury comes from the ancient Roman god Mercury (Mercurius). Mercury is the god of commerce and symbolizes swiftness. Because Mercury is the fastest-moving planet in the solar system, it was given this name. The idea that Mercury shines blue is a misunderstanding.

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Hoshino Takashi

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Many cosmetic ingredients are derived from petroleum.

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Many cosmetics use petroleum-derived ingredients. These are widely used because they are more stable and more cost-effective than plant-derived alternatives. Examples include mineral oil, paraffin, and petrolatum (Vaseline).

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Hoshino Takashi

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Litmus paper turns blue when it reacts to an alkaline solution.

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Litmus paper, which is made from lichens such as litmus lichen and Parmelia (Xanthoparmelia), turns red in acidic solutions and blue in alkaline solutions. Using this property, it distinguishes whether a solution is acidic or alkaline.

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Hoshino Takashi

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