Rikaido is a free, browser-based service that helps friends explore how well they know one another through personalized two-choice quizzes. Users choose their own answers, create a quiz, and share a link; friends then guess which option the quiz creator would pick. Results show each participant’s score, rankings, and understanding by topic, turning everyday preferences into a playful social activity.

Quizzes can range from 30 to 150 questions, with themes including food, relationships, personality, habits, gaming, social media, school, fandom, and more. Rikaido also offers themed editions, a 16-type personality quiz based on responses, and community statistics showing how people answer popular two-choice questions. No account or app installation is required, and quizzes can be shared through services such as LINE and X.

The site describes scores as a measure of matching answers, not a scientific assessment of friendship or compatibility. Rikaido also publishes guides and articles about using the service and interpreting quiz results