Alternate form for the hiragana そ

So I was attempting to read a manga in Japanese to test my proficiency, and I was pretty proud that my training has paid off, as I immediately recognized ようこそ (welcome)。However, as I looked at the hiragana for "そ", I noticed that something was off about it.  It had a small mark on the upper left side similar to what I see in the hiragana お.  I tried to find a small version to copy and paste, but no luck!  And sadly, changing my keyboard to type in Japanese doesn't allow me to type that alternate form either, so you get a link.

https://en.wikipedia.org/wiki/So_(kana)

The last hiragana form is stated as an "alternate" form.  Now my question is, can it be used today, or is it something that is out of practice and just around to preserve the history of the origin of hiragana?  Unlike the "alternate" forms of き and さ (which is strictly for computer font and not meant to be used for writing), the alternate form of そ is not in the same category.  So my question is, when and why did that alternate form change to the more common form that we have today?  Is there any interesting history behind it?  And why isn't it taught anymore?
 

こんにちは Trutenorさん!

Thank you for your question. This question is still brought up by native Japanese speakers today as well.

The alternate form of "そ" (along with the alternates for き and さ) is still used today. It seems that people from the older generation was taught that alternate form in primary school, while the younger generation was taught the more modern, common form.

This does not mean that the older generation always uses the alternate form (or vice versa), it seems to be based on one's preference (and handwriting style as well).

There does not seem to be a reason as to why it has changed to the form we have today but it was probably to make it easier to write. At the end of the day, there is no particular kana you should use, as long as everyone can understand which kana you are using :)

Good job on reading a manga in Japanese! これからも　がんばって　ください！

Crystal

どもありがとうございます Crystalさん！

Well from your explanation, it seems to make a bit of sense.  The premise of the manga that I read was that a high school boy was moving over to the countryside to live with his grandfather.  The village that they lived in was extremely old fashioned, and lacked most modern technology.  Perhaps the alternate hiragana of そ was meant to emphasize that?