ichinoue:

One of the first things that stood out to me about ichihime was how protective Ichigo was over Orihime as early as chapter 3. He says they’re not close, she’s just a friend of a friend, etc. and yet

He’s the one to bring attention to her injuries, and then chastises her for not being more careful, because as we learn in the following pages, he worries about her. He’s already protective over her well-being, so much so that it exasperates him.

“More than often! It’s almost every day!” Clearly, he’s been paying attention to her every day, even though she’s just a friend of a friend (they cut this part out of the anime). And then he scolds her again for not being more careful. He does these things because he cares. We know this because:

He admits to looking after her, and even wears himself out worrying about her, and wondering if she’s alright (yet another part that was cut out of the anime). Kubo was definitely setting the groundwork for something here. We just learned in the previous chapter that Orihime likes Ichigo, and now here Ichigo is, caring about Orihime so much that it wears him out.

For him to be this protective over her, this early on, when ‘they’re not close, she’s just a friend of a friend,’ - well, it’s no wonder that later when they become closer, he makes an exclusive vow to protect her and even rises from the dead to keep that promise (both times using the same form of ‘mamoru’ that has a sense of permanence attached and shares kanji with his name). Even after becoming a hollow, his desire to protect her still resurfaces, as if it’s instinctual to him.

Protecting is such a huge part of Ichigo’s character, so for his caring over Orihime to be established this early on, and his protectiveness over her to be emphasised more than any other character at various times throughout the rest of the series—it’s all highly indicative of his feelings for her, in my opinion.