"Two-character compound word fill-in-the-blank puzzle ~Nijiume~" is a puzzle game where you guess the kanji that is common to four two-character compound words.

It is also called ``Wado Kaichin'' because of the similar layout of the square hole and the kanji.

This is a classic kanji quiz that is asked on junior high school entrance exams and on TV programs.

□Beginner and advanced□
There are two levels of rainbow plums: "beginner" and "advanced".

``Beginner'' only includes idioms that most working adults know.
Even if you are not confident in your kanji, you can enjoy it like a puzzle.

``Advanced'' includes a lot of technical terms from various fields.
To answer correctly, you will need a wide range of knowledge and the ability to guess unknown idioms.
If you can't solve it at all, it's okay to look at the answer and study.

□Hints and answers□
If you can't think of just 4 characters (top, bottom, left, right), you can see up to 2 "hints".
If you can't figure it out even after looking at the hints, you can also look at the "answer".

□Convenient Internet search function□
When you get a correct answer or look at the answer, you can search the Internet for the meaning of the idiom by tapping on the surrounding kanji.
Recommended for people who say, ``I got the answer right, but there's an idiom I don't know...'' or ``I can't understand it at all, but I want to study.''

□Easy-to-read question selection screen□
On the first problem selection screen, you can see at a glance the number of questions you have not seen yet and the number of questions you have solved.
The next selection screen shows you the status of each question, including whether you used any hints.

□The secret to fun□
You might think that this kanji puzzle is easy to make by just choosing four idioms.
In fact, if you don't think carefully about it, the following problems will occur.

- You can't enjoy it as a quiz because you know the answer right away.
・I don't feel like I've solved the problem because I get multiple answers (this is called "multiple answers")

However, the questions asked in this app were carefully created over time by Kyoto University graduates who hold the pre-1st grade of the Chinese proficiency test.
Therefore, you should be able to take the quiz seriously and enjoy a sense of accomplishment.

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□About definitions and usage standards of idioms□
Idioms or words are difficult to define, and there are various theories, but in this app, based on the ``subjectivity of the creator'', two kanji that meet the following criteria are generally accepted as idioms.
However, proper nouns and words with okurikana, such as those found in Japanese dictionaries, are only taken into consideration when confirming multiple answers.

・Only vocabulary listed in medium-sized Japanese dictionaries (Kojien, etc.), or technical terms, new words, slang, etc. that are allowed to be used to the same extent are permitted.
(Example) "Hangao", "Bito", etc. are acceptable.

・Proper nouns and number words are not allowed unless they have been converted into common nouns.
(Example) "Ingen", "Ikki", "Shiki", etc. are acceptable.

・Pronouns, adverbs, and foreign words are allowed as long as they are two kanji characters.
(Example) "Sesha", "Nasara", "Coffee", etc. are acceptable.

- Abbreviations are allowed if the abbreviations are well-established.
(Example) "Tenkotsu (= job change activity)", "Makitsu (= manga cafe)" etc. are acceptable.

- Items that would normally be allowed to include okurigana will not be accepted.
(Example) "Yakiniku", "Kirikae", etc. are not allowed.

- Tatami language is not accepted.
(Example) "Iroiro (=various things)", "day day (=days)" etc. are not allowed.

*"Kanjiken" is a registered trademark of the Japan Kanji Proficiency Testing Association, a public interest incorporated foundation.