kz

Relative path does not work.
Specify absolute path like this:
<img src="http://www.justchacha.com/images/foods/coffee2.jpg" />

Add Japanese fonts to font-family in style.css:

body{
font-family:"ヒラギノ角ゴ Pro W3","ＭＳ Ｐゴシック",Verdana,Helvetica,Arial,Geneva,sans-serif;
}

<?php
// sticky section
$sticky=get_option('sticky_posts');
query_posts('p=' . $sticky[0]);
  /* do stuff */
wp_reset_query();
// main section
global $wpdb;
$posts = $wpdb->get_results
("
  SELECT *
  FROM $wpdb->posts
  WHERE
    post_status = 'publish'
    AND
      ID IN (
	SELECT DISTINCT post_parent
	FROM $wpdb->posts
	WHERE
	  post_parent > 0
	AND
	  post_type = 'attachment'
	AND
	  post_mime_type IN ('image/jpeg', 'image/png')
      )
    ORDER BY post_date DESC
");

foreach($posts as $post) :
  setup_postdata($post);
?>
<div>
  <span class="slider-text">
    <h3><a href="<?php the_permalink(); ?>" rel="bookmark" title="<?php the_title(); ?>"><?php echo slidertitle(get_the_title());?></a></h3>
  </span>
  <div class="slider-image">
    <?php
    $images = get_children(array(
      'post_parent' => get_the_id(),
      'post_type' => 'attachment',
      'post_mime_type' => 'image',
      'orderby' => 'ID',
      'order' => 'ASC'
    ));
    $ids = array_keys($images);
    echo wp_get_attachment_image($ids[0]);
    ?>
  </div>
</div>
<?php
endforeach;
wp_reset_query();
?>

1)Use
<?php echo wp_get_attachment_image($attachment->ID); ?>
or
<img src="<?php echo wp_get_attachment_image_src()($attachment->ID); ?>" alt="" />
instead of
<img src="<?php echo wp_get_attachment_url($attachment->ID); ?>" alt="" />

<?php
global $wpdb;
$posts = $wpdb->get_results
("
  SELECT *
  FROM $wpdb->posts
  WHERE
      post_status = 'publish'
    AND
      ID IN (
	SELECT DISTINCT post_parent
	FROM $wpdb->posts
	WHERE
	  post_parent > 0
	AND
	  post_type = 'attachment'
	AND
	  post_mime_type IN ('image/jpeg', 'image/png')
      )
    ORDER BY post_date DESC
");

foreach($posts as $post) :
  setup_postdata($post);
?>
<div>
  <span class="slider-text">
    <h3><a href="<?php the_permalink(); ?>" rel="bookmark" title="<?php the_title(); ?>"><?php echo slidertitle(get_the_title());?></a></h3>
  </span>
  <div class="slider-image">
    <img src="<?php echo wp_get_attachment_url($attachment->ID); ?>" alt="" />
  </div>
</div>
<?php
endforeach;
wp_reset_query();
?>

<?php wp_list_pages('depth=1'); ?>

1. style.css, line #161
2. font-size:3.6em;
3. font-size:2em; /* specify font size you want*/

Use below code after $attachments = get_posts($args);.

if(count($attachments) > 0) :
foreach($attachments as $attachment) : ?>
<div>
  <span class="slider-text">
  <h3><a href="<?php the_permalink(); ?>" rel="bookmark" title="<?php the_title(); ?>"><?php echo slidertitle(get_the_title());?></a></h3>
  </span>
  <div class="slider-image">
    <img src="<?php echo wp_get_attachment_url($attachment->ID); ?>" alt="" />
  </div>
</div>
<?php endforeach; else : ?>
<div>
  <span class="slider-text">
  <h3><a href="<?php the_permalink(); ?>" rel="bookmark" title="<?php the_title(); ?>"><?php echo slidertitle(get_the_title());?></a></h3>
  </span>
</div>
<?php endif; endwhile; endif; wp_reset_query(); ?>