You could try 'Sweet Embrace'. It has a similar style of depicting love and emotional connections, much like in 'Kiss Hug'. The art and narrative might appeal to you if you enjoyed the latter.
You might find 'Starry Night' comparable. Both share similar emotional depth and storylines centered around complex relationships, similar to what you get in 'Wakeari Kiss'.
Perhaps 'Ao Haru Ride' is similar. It has a similar focus on the ups and downs of young love and the challenges characters face in expressing their feelings, much like in 'Forbidden Kiss'.
One manga that could be similar is 'Watchmen'. It shares elements of dark themes and complex characters like Batman.
One manga that might be similar is 'Parasyte'. It has elements of horror and action, like Gantz, and explores themes of survival and humanity's response to strange threats.
I think 'Fruits Basket' could be similar. It has a similar emotional depth and character-driven storylines like 'Swan'.
I think 'Love Hina' might be somewhat similar. It has elements of romance and character development like in Sextudy.
I think 'School Days' could be somewhat similar. It has similar elements of complex relationships and emotional turmoil.
Well, 'Parasyte' could be a manga similar to Kaijii. Both have elements of horror and mystery, and the character development is quite engaging in both.
It's hard to say exactly. But you might want to check out manga like 'Attack on Titan' as it shares some similarities in terms of intense storylines and complex characters.
Well, 'My Hero Academia' could be similar. They share elements of adventure, diverse characters, and a focus on personal development and facing challenges.