A hajidere refers to a character who is very, very nervous and embarrassed around their crush.
Hajidere characters basically get nervous around their crush like a dandere character would, but it is set to extreme. They will constantly blush near their love interest, and might even faint from being so bashful. They have a ton of trouble confessing, so the love interest should make the first move. Although if the love interest does, the hajidere might faint before they answer. However, they can be social and outgoing in front of everybody else, unlike a dandere.
Meaning of the Name
This word is a compound of "haji" (恥), which means embarrassment, and "deredere" (デレデレ), which means "lovey dovey".