Every one of the above responses contain excellent advice for your new addition! I love that name, so unique!
Members have already mentioned some of these, but this is just what I would do myself in your situation. I would confine Renji to one room, preferrably your bedroom; because it has your scent and this will become a familiar thing to him, a comforting thing, and before you know it, he'll be seeking you out for comfort! Put food, water, and a litterbox in your bedroom along with some toys. That's another thing; kittens have lots of energy and need lots of stimulation! It is preferrable to have an older cat along with a kitten, but of course not completely neccessary. But if you don't, you need to spend an extra alot of time with Renji, playing! Foil and paper wads, yarn, cardboard boxes, stuffed animals, flashlights all are great toys you can find in your own home. Spend alot of bonding time with Renji; pet him, brush him, sit by him when he eats, and play with him until he gets tired, then put him in your lap so he'll sleep by/with you, this is also a good bonding method. Once Renji is seemingly comfortable with you, try confining him to two rooms. Gradually open up the spaces and show him new areas of your house. Remember to spend about 2 hours a day with Renji even once he is comfortable in the house, playing and bonding with him. You also said that if you get down to his level, he is more likely to come to you. Well, think like him! What if you were a shy, little kitten, a tiny thing taken away from everything comfortable and everything he knows,a nd all of a sudden launched into a new life! New smells, sights, textures, sounds, there are even PEOPLE! It's very intimidating... Just be patient with Renji, he'll come around. Good luck and give him a kiss on the nose for me!