There's Something Weird In My Bikini Armor!

From Comiket 88.

A glitch in the virtual reality game was making him wear bikini armor. It got worse when he was attacked by parasitic tentacles.
Thousands of tiny squirmers took root in his barely-useful brassiere and thong, dancing on his nipples and up his butthole......
When the wriggling finally subsided, he still had to face the Orc Boss.

Tentacle Armor x Shonen Original Manga
22 pages + afterword, color cover, alt cover