Welcome to the fourth lesson in the series! Today's new kana will be easy, and look familiar. Take a look at the chart so far and the lines in bold since we'll review those.
あ い う え お
か き く け こ (+'k')
さ し す せ そ (+'s')
た ち つ て と (+'t')
な に ぬ ね の (+'n')
は ひ へ ふ ほ (+'h')
ま み む め も (+'m')
や 　 ゆ 　 よ (+'y')
ら り る れ ろ (+'r')
わ 　 を 　 ん (+'w')

Yes, we're doing 25 kana at once but you have seen them all before! By adding diacritic marks to the kana on the k, s, t and h lines, you can adjust the sound they make. Japanese use two sorts of marks: dakuten and handakuten. Dakuten (or just ten-ten for short) are most often used and appear as two short dashes ◌゙. Handakuten is used on the h line and appear as a circle above kana like this ◌゚. Diacritics can be used on other kana but it's rare and mostly in specialised dictionaries and sometimes for singing.

か (ka) → が (ga)
さ (sa) → ざ (za)
た (ta) → だ (da)
は (ha) → ば (ba)
は (ha) → ぱ (pa)
You can see we're looking at the g, z, d, b and p lines which are same as k, s, t and h lines. Luckily the h line is re-used! Let's speed through these.

が as in 'guy',
ぎ as in 'geese',
ぐ as in 'goose',
げ as in 'game',
ご as in 'go'

ざ as in 'zap',
じ as in 'jeans',
ず as in 'zoo',
ぜ as in 'zebra',
ぞ as in 'zone'

だ as in 'dummy',
ぢ as in 'jeans',
づ as in 'zoo',
で as in 'day',
ど as in 'dough'.
ぢ and づ sound the same as じ and ず. For now, it is safe to assume if you hear / ji / or / zu /, you write じ or ず as they are much more common than ぢ and づ.

ば as in 'bye',
び as in 'beer',
ぶ as in 'boo',
べ as in 'bay',
ぼ as in 'boy'

ぱ as in 'papa',
ぴ as in 'pier',
ぷ as in 'pool',
ぺ as in 'pay',
ぽ as in 'pole'

And here's today's homework:

• • Watch the video, and match the shape with its sound. You can see the next lines of kana on the chart
• • Follow the stroke order and write it on your own on a piece of paper 10× times or more. Gridded paper can help you get the proportions correct which you can download and print here.
• • Then, write it down again without looking at anything.
• • Come back in 3 days to repeat Task 3. Set a reminder on your calendar while you remember!
• • It's time to review the second fifteen kana again to refresh your memory!