Mecha-ude

These both fall under what I would describe as 'passion projects'. The animation/artstyle can be a bit rough around the edges, but also has some pretty cool aspects if you can look past that. Both of them star a boy, a girl, and some sort of kinda freaky monster/robot companion, and the big plot of each is that the main character(s) take on another, antagonistic boy with another monster/robot (leading up to a cool fight scene climax). The character archetypes are kinda similar between the two in general, except the genders are swapped on the mains. Both also have some big-name artists for the ED (Eve and supercell respectively) Unfortunately, while Cencoroll is continuing to receive sequels (after a lengthy hiatus), as of writing this there has been no further news on Mecha-Ude after the initial pilot's release. read more 

both anime are about people with mechanical robots attached to them . both anime have shy and unconfident main-character that only act when they are on trouble.  

Not only did Eve (the arguably best singer ever) participate in both projects, but the art styles of both are very similar. Plus, the main characters and side characters act very similarly to one another. 

Charming short science-fiction passion projects that ended up being developed further into a full release, invokes plenty of mystery and intrigue about the universe they take place in as well 

It has a vaguely similar MC and even his weapon has a golden flame like glow to it and the heroine is a similar cool headed type character with weapons comming out of her skirt. 

Both are smaller budget, short one episode OVAS by amateur or newer staff, featuring over the top action, highly stylish visuals and a very strong sense of passion behind their project. If you're someone who finds a lot of big budget anime rather stale these days, check out these passion projects, at a half hour each the time commitment is quite low, so you don't really have anything to lose trying either of them out.