When you're attacked by a stranger, you may not always be able to call for help right away.

It can be dangerous if you don't use quick judgment to protect yourself.

Japanese personal trainer Rikito Ohguro (challenger.ricky), who introduces self-defense techniques on TikTok, posted a video on what to do when a stranger suddenly grabs your arm.

If you know the technique and have practiced it well, there's a high likelihood you'll be able to easily escape.

@challenger.ricky #CapCut 体重差あってもできるよ?もしもいきなり掴まれたらぜひやってみてね♫コメント欄に解説します?@juria96210 #護身術 #対処法 #selfdefense #空手女子 #女子高生 ♬ 三原色 - YOASOBI

This move involves lifting up your grabbed arm in a diagonal upward motion to escape from your assailant's grip.

The key is to focus on the assailant's thumb joint and lift up your arm quickly and vigorously in the opposite direction! As you can see in the video, if you're smaller and weaker than your assailant, you can also add extra power by assisting the lift from beneath with your other hand.

It's a little trick that could really be useful to remember in a pinch.

The video elicited comments such as "I want to practice this" and "I learned a lot!"

It might be a good idea to practice this with a family member, friend or schoolmate first.

Rikito Ohguro has nearly 4 million likes on his TikTok channel, which features many other useful self-defense tips.

For example, here, he shows you how to escape from an assailant who tries to grab you from behind:

@challenger.ricky #CapCut 護身術とは逃げる為の技。後は走って逃げよう！！♫解説はコメントに?#護身術 #selfdefense #対処法 #痴漢 #空手女子 #女子高生 #対処する方法 @juria96210 ♬ Gee - Girls' Generation

You'll also find tips on escaping from various other situations, so if you're interested in self-defense, check out his TikTok channel.

Ohguro's assistant in the video (pretending to be a high schooler) is karate champ Juria Nagano, who also has her own channel here.