It is not 'シ'(し) but 'ツ'（つ）. Their figures are similar. The difference is the angle of the two short lines. I think the lines of ’シ' are a bit horizotal than 'ツ' . And the lines of ’ツ' are a bit close vertical. And small 'ッ' is exist. But typically not small 'シ' is not exist.
Japanese alphabet. line of Sa サシスセソ（さしすせそ） line of Ta タチツテト（たちつてと）
I will assume you meant katakana when you addressed a second syllabary.
Hiragana is usually only used for grammar, particles, etc.. Nouns, adjectives, verbs, etc., are usually written in Kanji. There are no Kanji for foreign words, which makes sense, right? That's why they have a second syllabary for foreign words. If they were to use Hiragana for foreign words things would get very complicated, you couldn't always tell grammar from foreign weird.
So in order to distinguish grammar and foreign/lean words (words without a Kanji) they have Katakana.
Remember that the Japanese language doesn't have as many sounds as English for example, so the words they create in Katakana don't always seem to resemble the original word.
That's all correct in terms of how they are used nowadays, but I'm not sure that's how the usage actually came about.
I'm definitely not a historian, but I think katakana existed even before the Japanese opened their borders and began interacting with the rest of the world. I read somewhere that it was primarily a script used by men, while hiragana was primarily used by women. No clue about the accuracy of that idea, but I'm curious if someone else knows.
A source quoted in sora's link adds a bit of detail:
the soft, curvy nature of hiragana was thought of as womanly, so only katakana and kanji were used in official documents for a very long time.
Sorry, as ss says it means "off topic". It's a bit ot because it doesn't address the topic of small kana, but rather that of the presence of two syllabaries. Not completely ot because you wrote two lines in the 2 syllabaries.
So ... why is there a separate syllabary for loan words?
(And why is it so hard to find previous comments in the mobile app?)
I wrote two lines because to show the difference of shape 'ツ' and 'シ'. It is not relation to syllable.
If you want to talk the different topic, it is good you do not use the 'reply'. it was confuse.
And the small 'ツ' is the same pronunciation to the small 'つ'. The sound is used Japanese words as well.
Here's a tip: compare し to シ and つ to ツ. When you see either of these katakana, visualize at which side the two small lines line up with the curve. If they line up at left, you can draw a し at the start of each line. If they line up at the top, you can draw a つ at the start of each line.
Middle character is small " tsu " つ（ツ）sometime use for middle alphabelt when double Like Petto Netto Nippon www.textfugu.com/season-1/reading-writing-memorizing-hiragana/4-8/
I'm not familiar with that extension, but in most IME settings, the small characters will generally appear automatically if you type the correct Hepburn romaji for the relevant kana combination, e.g. sha becomes しゃ, and petto becomes ペット (the ッ appears because of the doubled-consonant). If you need to force a character to be small, you can generally type "x" or "l" before the character (this only works for some characters I believe), e.g. xyu becomes ゅ.
The line is easy; just type a dash/hyphen.
It's very uncommon. Usually, you would see it in onomatopoeic verbs like イライラする ("to be irritated"), or loan words with the -っぽい suffix (meaning "-like") such as パソコンっぽい ("computer-like"). It also sometimes occurs stylistically in manga or advertisements to add emphasis to particular sounds.
The Japanese ペット is exclusively a noun.
The verb for "to pet" is a bit tricky. It can be なでる (but that's more like "to stroke" or "to caress") or たたく (but that's more like "to hit" or "to strike"). Alternatively, you could say パットする (literally "to do a pat"), but as far as I'm aware ペットする doesn't exist in Japanese, or else it means "to pet someone/something (as in, to strike with an animal)" :/