you have to call a special command for registering the airdrop
To receive airdrop:

from the download page on official website,
  https://neetcoin.jp/en/download-2/
download the wallet appropriate to your OS
↓
run the wallet, and copy your NEETCOIN address from "Receive coins"tab
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at airdrop application form,
  https://neetcoin.jp/mynt/?la=en
click "Sign up" and read the instructions, and register.
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login and register for the airdrop( click "Register for the airdrop" button), and get your registration command.
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at #neeko channel at this Discord's room,
(you can see the channel on the left side of this screen)
enter your registration command like below.

!neetaircode YOUR_PASS_CODE

if succeeded, you'll get a reply from neeko