7.1 Kanji Set A — Numbers, Time & Calendar

On'yomi vs Kun'yomi: Why One Kanji Has Two Readings

Chapter 2 gave you a reference table of roughly 100 kanji with their basic readings. This section goes deeper: it teaches you to read number, time, and calendar kanji the way JLPT N5 actually tests them — inside compounds and with the sound changes that trip up beginners. Nearly every kanji carries two kinds of reading. The on'yomi (音読み, on-yomi, the Chinese-derived 'sound reading') dominates in multi-kanji compounds; the kun'yomi (訓読み, kun-yomi, the native Japanese 'meaning reading') appears when a kanji stands alone or takes a hiragana tail. The number 一 (one) shows the split cleanly: on'yomi いち (ichi), kun'yomi ひと (hito) as in 一つ (ひとつ, hitotsu, one thing).

The core numbers 一 through 万

The right-hand column is the whole game. N5 deliberately picks compounds where the 'obvious' number reading is wrong. 四 is normally し, yet 四月 is しがつ (shigatsu, April) and 四時 is よじ (yoji, four o'clock) — never よんじ. 七 is しち, so 七時 reads しちじ (shichiji), not ななじ. 九 flips between readings: 九時 is くじ (kuji, nine o'clock) and 九月 is くがつ (kugatsu, September), but 九日 is ここのか (kokonoka, the 9th).

Counters Change the Sound of the Number

When a number bumps into a counter, the joint often mutates — a doubled consonant (gemination) or a voiced/semi-voiced shift. This is why memorizing the bare table from Chapter 2 is not enough. Study the four calendar-and-clock counters below; they generate a large share of N5 reading and listening items.

Notice that 〜時 (o'clock) and 〜月 (month) share the same three exceptions — 4, 7, 9 — because they descend from the same historical readings. Learn the trio 四・七・九 once and it pays off in two counters at the same time. For days of the month, the first ten days plus the 20th use native (kun'yomi) counting: 一日 (ついたち), 二日 (ふつか), 三日 (みっか), 四日 (よっか), 五日 (いつか), 六日 (むいか), 七日 (なのか), 八日 (ようか), 九日 (ここのか), 十日 (とおか), 二十日 (はつか). From the 11th onward (except 14, 20, 24) the pattern becomes number + にち: 十一日 (じゅういちにち).

Day-of-Week Kanji: The Element Logic

The seven weekdays are built from a repeated block, 曜日 (ようび, youbi, 'day of the week'), preceded by an element or celestial-body kanji read in its on'yomi. This is why the standalone kun'yomi you learned (火 = ひ 'fire', 水 = みず 'water') does not appear here.

Now, Week, Half, and the 午 Family

Rounding out the calendar set are the framing kanji. 今 (いま / こん, now) builds 今週 (こんしゅう, this week), 今月 (こんげつ, this month), and the irregular 今日 (きょう, today) and 今年 (ことし, this year). 週 (しゅう, week) gives 先週 (せんしゅう, last week), 来週 (らいしゅう, next week), and 毎週 (まいしゅう, every week). 半 (はん, half) makes 半分 (はんぶん, half a portion) and 二時半 (にじはん, half past two). 午 (ご) never stands alone; it forms 午前 (ごぜん, AM / before noon) and 午後 (ごご, PM / afternoon), pairing with 前 (まえ, before) and 後 (あと / うしろ, after / behind).

Worked 漢字読み Items (Choose the Reading)

The N5 vocabulary section opens with 漢字読み (kanji reading) questions phrased exactly as: 「つぎのことばの よみかたを えらんでください。」 ('Choose the reading of the following word.'). You see a word written in kanji and pick the correct hiragana. Here is how to reason through real examples from this kanji set.

Worked item — 毎日: The four options are まいとし, まいにち, まいしゅう, まいつき. The prefix 毎 (まい, every) is fixed, so the second kanji decides everything: 日 = にち (day), 月 = つき/げつ (month), 週 = しゅう (week), 年 = とし (year). Because the word ends in 日, the answer is まいにち (mainichi, every day). The distractors are all real words (every week / month / year), which is why you must read the second kanji, not guess from 毎 alone.

Worked item — 何時: Options なんにち, なんがつ, なんねん, なんじ. 何 (なに/なん, what) combines with a counter to form a question word: 何日 (which day), 何月 (which month), 何年 (which year), 何時 (what time). The kanji 時 means 'time/hour', so 何時 reads なんじ (nanji, what time). Watch the vowel — なんじ, not なんぢ — and note that 何 shifts to なん (not なに) before a counter.

Worked item — 半分: Options いちぶん, はんぶん, ぜんぶ, すこし. 半 is はん (half) and 分 here is ぶん (part/portion), so 半分 = はんぶん (hanbun, half). The trap ぜんぶ (全部, all) and the vocabulary word すこし (a little) are meaning-based decoys, not readings of 半分.

Worked item — 来週: Options こんしゅう, らいしゅう, せんしゅう, さらいしゅう. All four end in しゅう (week); the first kanji sets the time frame. 来 (らい, coming/next) gives らいしゅう (raishuu, next week). Compare 今週 (this), 先週 (last), 再来週 (the week after next). This 'fix the tail, read the head' method works for the entire 週・月・年 family.

Worked 表記 Items (Which Kanji Spells the Word?)

The 表記 (hyouki, orthography) task reverses the direction. The stem is 「つぎの ことばは かんじで かくと どれですか。」 ('When the following word is written in kanji, which is it?'). You get a hiragana word and choose the matching kanji from four look-alikes.

• むいか → 六日: Options might be 六日, 八日, 四日, 九日. Because むいか is the fixed native reading of the 6th, the answer is 六日. Knowing the day-of-month readings backwards is what makes this instant.
• ごぜん → 午前: Distractors reuse look-alike kanji such as 牛 (cow) for 午, or swap 前 (before) for 後 (after). Only 午前 (AM) matches; 午後 would be ごご.
• ** さんじ → 三時**: You must reject 三時 vs 山時 (the number 三 versus the look-alike 山, mountain) and 時 vs 持. The correct spelling is 三時 (3 o'clock).

Common Traps to Rehearse

1. 4 / 7 / 9 read differently by counter. 四月 しがつ but 四時 よじ; 九月 くがつ but 九時 くじ. Never default to よん or きゅう in these compounds.
2. Day of month ≠ day of week. 六日 (むいか, the 6th) is a date; 六曜日 does not exist — only 月〜日曜日 are weekdays.
3. Elements switch to on'yomi in weekdays. 火 alone is ひ (fire), but 火曜日 is かようび.
4. 今日 and 今年 are irregular. They are きょう and ことし, not こんにち/こんねん at N5 speed.
5. 半 vs 分. 半 (はん) means 'half' and stands after a clock time: 二時半 (にじはん, half past two). 分 (ふん/ぷん) means 'minute(s)': 二時十五分 (にじじゅうごふん, 2:15). Do not confuse 半分 (はんぶん, a half portion) with these clock uses.
6. 午前 vs 午後 in listening. Number traps like ごぜん九時 (9 AM) versus ごご九時 (9 PM) are extremely common — catch the first syllable ぜん (before) versus ご (after) before you commit to an answer.

Mastering this single set — numbers, counters, weekdays, and the 午/半/今/週 frame — reliably clears a large block of the vocabulary section, because these characters recur in nearly every reading and listening passage about schedules, shopping, and appointments.