The basics
In this section I'll explain how to use a Jinsei series Tamagotchi.
The buttons
Use the Ⓐ button (left) to make a selection. It lets you go from one option to another and change the letters / numbers when you are inputting data.
Use the Ⓑ button (middle) to confirm a selection. You can also use it to switch between Tamagotchi mode and clock mode.
Use the Ⓒ button (right) to cancel a selection or go back.
If you press Ⓐ and Ⓒ at the same time in Tamagotchi mode, you will be able to turn off the sound.
Choose "おん" if you want your Tamagotchi to beep or "おふ" if you want them to stay quiet.
If you press Ⓐ in clock mode you will be able to switch between 12-hour mode and 24-hour mode, and,
if you press Ⓐ and Ⓒ at the same time in clock mode, you will be able to change the date and time.
To set the time, press Ⓐ to change the selected number, Ⓑ to confirm it and Ⓒ to go back.
The date is in the Month/Date format!
In the Jinsei series, you can change the screen's contrast if you press Ⓑ and Ⓒ at the same time in clock mode.
(It's easier to hold Ⓒ and then press Ⓑ.)
Once you're here, you can increase the contrast with Ⓑ and lower it with Ⓐ.
Press Ⓒ to leave the contrast menu.
While the time is being set (with a number blinking), your Tamagotchi will be paused!
This can be useful if you have to leave them alone for a long time.
Your Tamagotchi won't grow while it's paused!
Unless you have to leave them for over 12 hours, it might be better to just change the time so they sleep instead.
You can use the reset button (behind) to reset your Tamagotchi.
This screen will appear if you press it.
Choose the first option (ろーど) to continue raising your current Tamagotchi.
Choose the other one (りせっと) to erase all the save data and start over.
This screen will also appear after you put a new battery in. (Sometimes you need to press the reset button after inserting the battery for it to turn on.)
You'll see this screen when you need to change the battery.
To do this, you must open the device's back cover by loosening the screw.
Click on the screw on the image above (the one showing a Tamagotchi from behind) to see what it looks like once you open it.
How to check your Tamagotchi's ROM version
If you hold down the Ⓑ, Ⓒ & reset buttons and then release the reset button while you keep holding the rest,
your Tamagotchi will enter test mode.
First, the screen will appear completely black. If you press Ⓐ, Ⓑ and Ⓒ in that order, you will see the screen change.
Press Ⓐ to see the ROM version screen.
If you press Ⓐ once again, the EEPROM will be tested and all save data will be lost (you won't lose it before this point.)
How to raise your first Tamagotchi
After turning on a Tamagotchi with no save data or deleting the existing data, you have to set the time.
After doing that, you have to write your birthday.
(Remember, Month/Date)
An egg will appear and, after a minute, your new Tamagotchi will be born!
Before being able to take care of them, you have to give them a name.
You will be able to use hiragana and 25 symbols.
Now you'll have a hungry and sad baby Tamagotchi… 
Use the care icons to raise them!
Press Ⓐ to choose an icon and Ⓑ to confirm your selection.